itinerary help

I think you may be mixed up, because that border crossing at Snuol / Loc Ninh is nowhere near Pleiku, rather it is on the way the HCMC.
In any case, I would say that your plans are way too ambitious - you want to go from Mondulkiri right up to Hanoi, then back down to HCMC, which is quite possible if you spend about 5 days straight of sitting on buses and trains, but you won't see anything of the country.

Just to add - I only just realised you had included Siem Reap / Angkor as well.
You have 16 days - which is a nice amount of time to stay in Cambodia only and visit Siem Reap, Phnom Penh, Mondulkiri, Kratie (and Kompong Cham on the way back to PP), which is exactly what I did on one visit to Cambodia.

Or you could do the main bits of Cambodia combined with Southern Vietnam. Have a look at a LP Vietnam because it has sample itineraries for a week. I've done quick trips but even I find your itinerary far too much. I think you under estimate the distances and time taken to travel.

As the others have said, I feel you are underestimating the distances (or time) it takes to get between places, please be aware that you spend the best part of a day travelling between major centres, even if it might only be 10km or so. for example the road from phnom penh to SR takes 7+ hours at present, you will also find the journey from SR to Kratie is similar and so on..So going by that you already have 10 days in Cambodia based on one day out to travel between places. Vietnam is a vast place and it takes along time to travel, it's certainly best to only go in one direction, you will have only a few days so pick your destinations wisely, maybe do as westodd suggests and stick to the south. Alternatively pick just one of those countries and enjoy it properly.

Spend all of your time in either Vietnam or Cambodia. One day to see the temples of Anglor Wat? You've got to be kidding. It is way too idealistic and simply won't work. Nothing personal but of all the idealistic itineraries this is the most unrealistic I've ever read. You might do it with a time machine, but certainly not with Asian transportation.

Take the advise above - I would have taken a month on Dales trip

thanks for the feedback, I was worried it was too ambitious. I like the suggestion of remaining in south vietnam as much as it sucks missing Hanoi. As I said, we're trying to find a flight to save a full day of land travel.
Thanks again!

thanks for the feedback, are you familiar with the border crossings around mondulkiri? Do you have any alternative suggestions?
As I posted in the general reply, cutting Hanoi out and making My Son the most northern point may make the most sense. This was the first edit of the itinerary which includes everything we wanted to see along a route - if only I had more vacation time!

That sounds like what we may have to do, missing north vietnam sucks but even planning the trip we didn't feel like it was going to be feasible to get up to hanoi