San Diego

We've been in San Diego for just two months and we've made three small trips already, two to LA to see my Mom and one to San Francisco to see friends, so we are closer to being tourists in San Diego than we are to feeling like residents. That will pass, of course, and we are in the process of changing our condo to make it feel more like home, but meanwhile I can talk about San Diego as if I was visiting.
To begin with, downtown San Diego is quite small, about one and a quarter miles square. You can easily walk from any corner to any other, which means that if you are staying anywhere in town, park your car and forget it. And like any city, you'll see a lot more and get more of the flavor of the town if you walk. By the way, I call it a town because that is the feeling downtown has. Only 35,000 people live in the area bordered by Interstate 5 even though the total population of the city is 1.2 million.
When you visit, you will want to walk down 5th street and experience the Gas Lamp District. While interesting during the day, night time is best as that's when the place comes alive. The restaurants are a bit more expensive than the rest of the city and the meals we have had have been pretty ordinary, but the atmosphere is something you'll want to enjoy.
The other night time area is Little Italy, a stretch of about six blocks on India Street not too far from the airport. As the name implies, you will find most things Italian including many restaurants. The food is better here but the selection is limited. Be in the mood for pasta.
During the day, our favorite stretch of downtown is the Marina area from Waterfront Park to Seaport Village. The village has a dozen small restaurants where you can grab lunch and almost always eat outside. San Diego has over 330 days of sunshine a year and even winter days are usually in the 60's. Unfortunately, Seaport Village is going to be torn down and replaced by a "resort". Chances are the charm will vanish with the wrecking ball.
If you enjoy ships, the waterfront has two ship museums: the Midway - a World War II aircraft carrier, and the Maritime Museum of San Diego, which has half a dozen different ships to tour including two submarines, a Spanish Galleon, and the Star of India, a three masted sailing ship. Either museum will take you at least four hours to see, and both are worth the time.
Downtown has an array of museums, shops, some interesting old buildings, and a set of new skyscrapers along the waterfront. The convention center is also located downtown, famous for its Comic-con.
You could easily spend two or three days without leaving the heart of the city, but most people are going to want to visit Balboa Park just a mile to the north. The park is large, famous for the San Diego Zoo, but also filled with museums, gardens, a lovely municipal golf course, and the Old Globe Theater: far too much to see in a day.
And there is more: Old Town San Diego, the birthplace of California; Coronado Island and the Hotel Del Coronado; Point Loma with its beautiful views, lighthouse, and early settlements; and many other places all still withing San Diego. Certainly more than we've been able to see even having been here 50 days.