Hi!
You can see a list of themes where the theme author has stated they are compatible with The Events Calendar here:
http://themeforest.net/attributes/compatible_with/events_calendar
Other theme marketplaces may have similar lists – broadly speaking though we enjoy compatibility with most themes which are built in line with current best practices – often the best idea is to try a few themes or ask the author before you buy (if it’s a commercial theme) to check in with them 🙂
Certainly if you find a theme you like and do a quick search here on the forum for the theme name you’ll probably find it there are any existing support threads in relation to it.
Does that help?