We had a great 3 month stay at Marcela's place in Hillcrest. We came over from Europe due to work, and travelling with a toddler we found the apartment very convenient.

Marcela is an excellent host, very easy to correspond with and service-minded. When the dishwasher broke down (with the toddler we depended on this being functional), they immediately replaced it with a brand new one. For those (like us) who like to cook at home, the kitchen is fully equipped with what you need.
There's a convenient laundry room on the same floor as well.

The place is close (walking distance) to a lot of good grocery stores, restaurants and coffeshops, and with a car you have all of San Diego at your disposal.
Commuting to UCSD is easy as the shuttle bus from UCSD's medical center in Hillcrest is a short bike ride away.

Highly recommended for longer (or shorter stays)!