#8 - Wow, I hope 18 months from now I can write a similar route based on my upcoming RTW trip! Sounds like you covered a ton of ground.
As for my response, it's easy because I've got it in a spreadsheet
I'm budgeting about $25,000 for 18 months, and that includes the cost of insurance, storage, etc. I've budgeted $5,000 to get me started again once I return home (or should I say "if I return home).

I'd skip the places that are easy to get to on shorter trips (for me central america) and the places that would eat into my budget quicker (Europe). So I'd probably take 6 months to work my way from Quito to Buenos Aires. Fly from BA to Cape Town. Take 6-months to go overland up East Africa to Egypt, then 3 months in India and 3 months in SE Asia. Then again having seen much of SE Asia on other trips, I might focus on China at the end, then head home via the Trans-Siberia Railway.

I'm in the same boat :)
My plan is to take a year to eighteen months and travel from the UK to South Africa... and live in a bit of luxury along the way! Planned on doing it next year, but looks like 2009 now... I don't want to travel around the world, I just want to travel through Africa :-) I would rather see and travel slowly that take in lots at once.
My tentative itinery is something like this which basically fits in with the "best" weather:
June / July / August - in Europe - Hiking; Slovenia; Italy; Corsica; Sardinia
September - Libya (can get a ferry to Tunis and go through Libya... I am hoping by the time I go independent visas will be allowed again!)
September/October - Egypt
November,December - Ethiopia
January - Kenya
Feb/Mar/Apr - Kenya/Uganda/Rwanda/Lake Turkana - I have three months to kill; probably learn to scuba dive and/or sail during this time! This is the only part of the trip where the weather isn't perfect.
May/June - Wilderbeast Migration
July/August - Kilimanjaro, Malawi, Zambia
August/Sept/Oct - Botswana/Namibia/Cape Town
And generally lots of hiking in between...
If you've that much moolah, try spending some time in Southern Africa: July/August/Sept-to-mid Oct are best in Zambia, Northern, Botswana and Namibia for wildlife viewing.

@niam - very inspiring. We are doing something very similar starting next year with £50k plus £600 / month rental profit income - not fixed timescale but a few years in mind. Chucking in our jobs. Won't be excluding Japan under any circumstances as I have a few firework displays too see there :-)
to the OP - regarding the loan - pay it off. It'll be the best thing youy have ever done. What you will be left with will be a huge amount compared to most travellers and being debt free is one of the most liberating experiences you can have. Imagine travelling the world, seeing all those things, then having the knowledge you have to return to a sizeable debt.
We (wife and I) have been saving for over a year so far and have 8 more months to go. The 1st 8 months was paying off all debts/credit cards etc. Set yourself tight monthly budgets. Put your spending money in it's own account/cash. Treat it as a challenge and it soon adds up :-)

Wanttotravel2007, our booking-planning process was pretty simple.
Hubby really wanted to do the tran-sib and did loads of research. We realised going to Estonia and then to Russia cost about 30GBP each whereas a flight to Moscow cost about 400 each. Depends on timing obviously. So we basically prebooked our hostel in Tallinn, our train tix as far as UB, Mongolia and booked hostels in St Petersburg, Moscow cause timings were tied up, due to train dates. We could have just turned up and done it, but like you we wanted some idea to start with. The rest of our planning included a scribbled list of countries we always wanted to go to. You could read some posts on here but don´t buy too many guidebooks in advance, they are heavy, bulky to carry and we didn´t use the Japan & India ones we bought!! You just want ideas really, and a list off the top of your head is as good as any. Check out some of those lists like top 10 places people like and just wander. Often the best places are the ones you know nothing about and which surprise you. We loved Laos and Lesotho for that reason. We had no expectations so we were pleasantly surprised!
Now, down the road I recommend planning no more than 1 week in advance unless you are going somewhere in peak season and it´s going to be rammed. ie. Macchu Picchu in July or Rio Carnival. In lots of areas you can just leave somewhere when you´re ready or stay if you´re loving it! So plan a bit for the first few weeks, until you get in the swing, and then have a vague idea of places you´d like to visit. Don´t forget you have to allow time to chill and not schedule yourself too much. The whole point is you can do whatever takes your fancy and sometimes you only know when you meet someone who´s just come back from there. Right now we´re in Quito looking at the map of Ecuador and just picking towns randomly, we´ll get a bus and see what it´s like. Sometimes that´s the best way!

Poster 10 - Thanks for posting your spreadsheet - it really help me get a few ideas for my organisation. Unfortunately, I like things to be organised - I even have different bank accounts for different things. One for general spending, one for saving for things like car insurance etc, one for general saving for future and now my gap year account which is with a bank that doesnt charge for taking your money out abroad!
Niam - Thanks - TBH, I dont think i have the confidence to just go with the flow. That and I would have my family worrying sick, which makes me worry more! Although the idea of it does sound fascinating and a great way to do things. Ill be 25/26 when I go. What is the safety like in Asia? I have some say its fine and others say it spells danger!??
niamhandcathal have said exactly what I thought when I read your post - they're out of time. That's the bottom line: you can throw all the money in the world at something but unless you take TIME to look around and soak it up you'll end up feeling cheated. We have a budget similar to yours for 4 of us and 12 months to fill but it's time we're lacking to see everything not money. Hey ho looks like RTW no.3 won't be that far off...
Watched the movie 'A Good Year' the other day - he asks his boss about the original Van Gogh in his vault: 'When do you ever look at it?' Plan your time and it costs what it costs.

If I had hands down had more money, I wouldn't spend it on posh accomidations and food (except for the occasional splurge). I would go to Antartica on this cruise, or one similar and I would go overland through Africa. Maybe with this company or something like it.
I would also go slowly through Europe, or at least hit the major highlights I was thinking about skipping.
And I'd still go every where else....I'd just go slower and longer.
Pay off your debts before leaving. There is nothing worse than returning home and being faced with large amounts of debt.
Ruth
What would I do? Well as I'm getting old and am still fairly fit and well I'd travel in places where the going is a bit rough and where I might not want to go when I am older. So where I wouldn't go would be Europe, North America, Australia and New Zealand. I'm saving these for my old age. I'm based in the UK I would think of:
1. Learning Spanish and spending all the time in South and Central America and Mexico.
2. Buying a Land Rover and spending the time in East and Southern Africa.
3. By rail to Moscow and TranSiberian with lots of stops and down to China then Vietman and SE Asia.
4. Rail to India and closeby countries some treking in the North and relaxing in the South and possibly onto SE Asia.
But of all things I want to take time and to be able to stay at places I like and change my plans if I want.
Also a possibilty to spend time in various Monasteries.
And then again perhaps a long sailing trans-ocean trip.
Am I going to live long enough?
Thanks for an interesting question.
Rory