I just moved out from Denver (Lowry) 6 months ago and got a place right on the beach at Mission and Felspar in Pacific Beach. I can try and give you my observations.

• Depending on the season every night (except for most Sunday and Mondays) the bar scene is quite active. If you are within a block or two of Garnet expect people to be yelling and drunk in the area. If you have double-pane windows it is fairly tolerable. I've never run into anyone aggressive. It is fun on the weekend to go out as there are many tourists in our age range.
• The cost of housing is pretty absurd. The prices in ocean beach within 1-2 blocks of the water are more reasonable (although they use to be much cheaper). I didn't want to be in ocean beach because most of it is over run with homeless. The prices in Pacific Beach near the beach have gone up big time in the past 16 months.
• Walk-ability is pretty good. The bus also runs every 15 minutes and is $2.25 for a ride or $5 for a day pass. Very easy to catch and uber. The smart cars can be rented by the minute and dropped off almost anywhere.. take one downtown to go out and take an uber back if you've been drinking.
• I personally find that PB has a decent college vibe in that there really is no college vibe town wise in La Jolla for UCSD students, so they will come down to PB. When I walk around PB I see a lot of guys who look just out of college or that are in their 30's and want to act like they just got out of college.

There are a few good coffee shops. Since you are from Denver you probably love beer and Barrel Republic is pretty sweet. I love that San Diego is a beer city. The gyms are kind of hit and miss. In Denver I was use to high quality clean gyms for a decent price. Here it seems nothing is air conditioned and I know that a few months of the year it can get quite toasty. The 24 hour fitness is kind of below par.

Positives of PB: - The weekends are always a blast. - Every time I'm on the boardwalk on my beach cruisers I feel like I'm on vacation. - My friends love to visit. We go to the beach, have a little fire on the beach, and hit up the bars. - Fun to move from the midwest and see so many tourists. There is a lot of shops and bars in the area.

Downsides: - The people in Pacific Beach are no where near as friendly as they are in the Midwest. I really miss meeting genuinely friendly and interesting people. I've met a lot of great people from meet ups and people that will take some adjustment. - The amount of homeless people is also a large adjustment. - Although it is cleaner than Ocean Beach, it can still get pretty dirty. People don't have as much respect for where they live maybe? I've heard some jokes about rats in PB, but haven't seen that so far. - There tends to be a decent amount of traffic when you want to get in and out of PB. - Tons of tourists on the boardwalk outside my building. - I really miss having things a bit spread out or even lawns. Bird Rock and La Jolla are a bit more spread out and have wider avenues. Bird Rock is close to the beach and close enough to PB if it is within your price range. - PB isn't exactly a place I'd want my girlfriend to walk alone in. If you can afford it I'd look at staying within 1-2 blocks from the beach and north of Law.. - Good housing is hard to find. You have to look daily on craigslist. The good places will go within 1-2 days of being posted. Finding a good roommate can be difficult. Sometimes people just put a for rent sign out and never even list them. So driving around can be good if you are looking for a place.