San Diego is a pleasant, popular place to live. It enjoys a warm, sunny climate year-round, and rarely dips below freezing. Near the coast, the temperature tends to stay in the 80s during the summer, but further inland, it can get much hotter.
An air conditioner is not necessary within a few miles of the coast, as it rarely gets uncomfortably hot, however many homes have them. Further away from the coast, air conditioners tend to get a lot of use during the summer. Heaters are present in almost all homes, but generally needed only during winter nights.
The city is large and broken into neighborhoods. Each neighborhood has its own distinct 'flavor', some being popular with partying college students and others with suburban families. Pricing varies extremely widely within the limits of the city as well.
Public transportation offers a convenient way to get from place to place in many parts of the city. However, some neighborhoods are much better than others when it comes to getting across town. Most areas have a local bus for grocery shopping or getting to school, though.
San Diego is built on a series of canyons which could not be practically turned into real estate when the city grew around them. For this reason, there are miniature nature preserves located in almost all neighborhoods. Most have trails where you can walk your (leashed) dog and enjoy the outdoors. For the nature lover, they are a great way to find a connection to your wilder roots without leaving the area.
Winter recreation areas can be found only an hour outside the city on Mount Laguna or in the town of Julian. Both of these areas receive regular snowfall during the winter and San Diego prides itself on being one of the few places in the world where a person can (cross-country) ski and surf in the same day.
House rentals in San Diego are as variable as the city, ranging from brand new construction to historic Victorians. Some neighborhoods have more standalone homes and others are dotted with condos, townhouses and apartments. The city is reasonably pet-friendly, with many rentals accepting cats, and a fair number accepting small dogs. Large dogs are not impossible, but will make your housing search more difficult. Breed restrictions are rampant, but some privately-owned facilities will allow 'controversial' breeds.
San Diego is a city of roads and hills, so if you plan to walk or bike a lot of places, choose your location carefully. There are not a lot of bike lanes and getting from one place to another on your bike usually requires a fair amount of fitness. However, there is easy, quick vehicle access to almost all parts of the city via the 6+ major freeways that comb through it.