here are some of my ideas for new sets:
bigger sets
petrol station - 1 or 2 cars, 3 axels petrol truck, building with cofe corner+shop , at least 4 pumps and car wash ,5 minifig, price around 75 - 90 eur
post office - main office, store room , post van or truck similar to new ambulance car,3 minifig, 40 eur
bus staation - touring coach, public transport bus, shelter and shop, 6 minifig,50 eur
supermarket - main building, delivery truck, forklift, 5 minifig, 40-50eur
smaller sets
touring coach - 3 minifig, 20 eur
public transport bus - 3 minifig, 20 eur
street sweeper - 2 minifig, 15 eur
delivery truck - 1 minifig, 15 eur
tv truck - 2 minifig, camera, 20 eur
pizza delivery car - 1 minifig , 10 eur
small truck - 1 minifig, 15 eur
flower shop - 1 minifig, 15 eur
fast food shop - 2 minifig, 20 eur
cars similar to police cars , but in civilian versions