1: These places are very touristic, unless you would like to see more foreigners then Thai people I (personally) would not go there.
2: The tour you are planning to take is a nice tour itself but if by any means you can afford it book a private tour. The tour on the website you refer to is shared with other people (and will most likely involve a compulsory shopping stop). But is is definitely a good idea to do a short cruise and see Ayutthaya, good pick!
3: There are plenty of options you could choose from in Bangkok, as you said you dont want to hang out in bars avoid the the "Patpong" and "Nana" districts.
At night you could start with a visit to the Suan Lum Night Bazaar near Lumpini for outdoor eating in the beer garden en perhaps some shopping (nice little small shops, go in the back to get the best deals).
Bangkok is of course famous for it's ladyboys so why not visit a ladyboy show? There is one at Mambo (Sukhumvit soi 22).
If you like something more cultural you should see the Siam Niramit Show which is the best in Thailand.
4: For now we are just an informative website and we don't offer any services ourselves (yet).
You are however encouraged to make hotel bookings through our website (as we get a small commission) but thats up to you.
Good luck and anything else you need to know feel free to ask.
FORUM 
