This may be too late for you but I stayed in one of those residences for a month while looking for an apartment. I really wouldn't recommend staying in one for 3 months as it is nothing more than a hotel room with a small kitchen area.

I felt miserable and couldn't wait to get out of there, even though it was convenient for maid service and all that. Now that I'm in my own apartment, I'd much rather forego the maid service than to go through that again.

As for recommendations, depends on which area you want to be in. You can also try www.rentxpress.it but they charge a bomb, but their serviced apartments look like 'real' apartments, just fresh towels and linen or something like that.

Good luck.