I can't remember if you had a trainer or were just borrowing one last year. I have a rubber mat underneath my trainer in a corner of a room. The rubber mat protects my light colored carpet and the trainer gets used to store the bike or to do any maintenance or repair work that I have.

I would say get something to protect the carpet at the entry way of your apartment - whether it be a rubber backed rug or something like that. I pretty often carry my bike in and leave it stashed in my foyer so that i'm not carrying a dripping or dirty bike immediately through the house. It gives me time to take my shoes off (I pretty much always take my shoes off on coming into the house to try to protect the carpets and wood floors)