We are traveling to Siem Reap for two nights before we travel on to Tokyo. We have contacted the hotel regarding visiting the Ankgor Wat temple sites. There seems to be a lot of down time in the packages offered by the hotel. We only have two nights and would like to see as much as possible. Are there other touring services available?
Thank you.

There is anything you want available ;-)
You can do it yourself...by bike,by tuk tuk,by taxi.It doesn't have to be through a hotel at all.
Anyway, your hotel should be able to organise it how you like..if not,I'd choose a different hotel.......Where are you staying?

We stayed at the Motherhome Guesthouse -wonderful hotel. They arranged everything for us including driver and guide. Our days were packed, no sitting around. We told them what we wanted to see and they did the rest. Very reasonable prices and an excellent guide named Chet. PM if you want his contact info. I would recommend a guide if you want to get the most of it.
We only have two nights and would like to see as much as possible. Are there other touring services available?
You don't need to fret about finding a guide. They'll find you.
You will see a number of travel agents in the main area of town who can book you trips. The real problem is the roads in Cambodia in that a road trip you think will take you maybe two hours might take you eight hours, and even longer if you have to do a detour like going via Phnom Penh.
Some people here will tell you that you need two days for Angkor Wat and all the small temples, etc. There is a lot to see and doing it all in one go is hard work.
I liked the town of Siem Reap itself and was content to chill out there for some days last year, just wandering around.
Negotiate with any tuk-tuk drivers you encounter for a tour of the temples. You will have no problem finding them or they will find you. It is important to find one you can communicate with well so you can tell them exactly which temples you want and/or what time period you want the tour (i.e. 8 am to 5 pm with a lunch stop). One reason for the down time is that it gets very hot mid-day so many tour companies assume tourists want to go early morning then return to hotel for several hours during the heat of the day and return later in the afternoon. By going directly to the drivers you can get around that.
It is definitely very hot mid-day. However, I like going to the temples during that time since many of the tour groups and those booked on tours through the hotels have gone back to town to avoid the heat. We usually start in the early morning (6-7 am depending) avoiding the more popular temples until mid-day. Have a leisurely lunch, then hit the Bayon, Terrace of the Elephants etc. Then go to Angkor Wat around 2-3 pm and finally Ta Prohm around 4 pm. You certainly won't have the main temples to yourself, but the number of tour groups will be less. Early morning is a good time to hit Banteay Srei, Banteay Samre and some of the outlying temples before the tour groups descend on them. Have lunch and then start with the more popular ones. Take into account that it takes about an hour to get out to Banteay Srei by tuk-tuk. If you want sunset or sunrise be sure to discuss it with the driver before hand. In fact the better you have mapped out what you want to see ahead of time the easier it is to negotiate a custom tour.
Since you only have one day, you will not be able to see a lot. So consider carefully what you want to see, how much you enjoy temples and how many you can fit in your timeframe.

Keep in mind that the drivers may not take you into the temples or provide information. Only a licensed guide may do so. Most hotels have regular drivers and guides that they use but even if you decide not to use a guide, I would recommend booking a driver through your hotel so you don't waste part of a day negotiating with drivers.