This might be inaccurate but so far from what I've seen in gameplay and from other posters. This is for freeroam.
You can enter:
The police station next to the impound lot
24/7 and liquor stores and gas stations
Tattoo parlors and clothes stores
You can't enter:
Fast food restaurants
Casino(has a 'coming soon' sign)
Edited by pokemon4ever, 17 September 2013 - 02:05 PM.