We stayed in New Bagan which is a bit further away from the part where tourists stay and cost us 15,000 kyat return in a taxi each night to go to the main restaurants area. This is quite high for Myanmar so I would recommend staying in Nyaung-U which means is walkign distance to the night life.
It is nice to hang out in Old Bagan. There is really famous veggie cafe which is in Lonely Planet called 'The Moon' but we liked the one across the street called Yar+Pyi because the owner and his family were really friendly and they served gauc and pop (gaucamole and popadoms); indian spice flavoured guacamole with popadoms. We stayed in here for hours having iced coffees, juices and escaping the mid-day sun.
Temple hunting - hire a moped and go full throttle in the dark at 5am to hunt for the perfect temple to get the classic sunrise shot. As we were not close our chosen temple, North Guni, it was a race against time to get there before sunrise, which was very exciting and made me feel like I was in Indiana Jones. We had no clue where we were going and were just following smaller and smaller tracks. It was one of the most thrilling things I have done in my life. It felt like a proper adventure.
If you are getting the boat from Bagan to Mandalay the boat goes from Jetty Street which is closer to this area also. You need to leave at 5.30am which is early but you get so see the river lit by moonlight and experience sunrise which is pretty sweet.
Balloons over bagan - www.balloonsoverbagan.com
It's a popular thing to take a hot air ballon over Bagan but is $320. Ouch!