As I said, the devil is in the details. While Denis claims that Santa Monica is "the worst", having lived here for a couple of years, and in west LA (that is a semi-official area, bounded by Culver City on the south, Westwood on the north, Santa Monica on the west and Century City on the east) for 7 years before that, I don't find it the worst at all. Prior to that I lived in Pasadena, before that Claremont. So I've progressively moved west
If she has to be at UCLA 5 days a week, I'd want to live fairly close. And no, Thousand Oaks isn't necessarily "the valley" proper - it is even further west/north. You're in Ventura County at that point. But it also depends on where you end up working. Some couples who have jobs in different locations split the difference, others live close to one or the other. Some live close to neither for some reason(s). I don't get that - the last thing I want to do is waste my life in a car commuting to work in LA. imho that makes the place unlivable.
The problem with SM/west LA for commuting is the stretch along the east border of SM and just east of the 405. There are *a lot* of people who work in SM and live east. So around 5pm (plus or minus 2 hours) too many people are trying to get east. The 10 can be a parking lot, and the main E/W streets (SM Bl, Wilshire, Olympic, Pico) can be gridlocked. It can be really suck. I've been caught in it before when I had to be someplace at that particular time, but I'm usually able to avoid it. And for some reason yesterday there was almost no traffic going east.
I live in SM, work in Playa Vista. I can commute by fwy or surface streets, max time is 20min. My fiancee works in Valencia, but only has to be there 2-3 days out of the week, and once she gets past the nasty Sepulveda Pass section it usually isn't a bad commute.
I love Santa Monica other than the high housing costs. I can walk to the beach and to a ton of great restaurants. The air is clean and temps are reasonable in the summer. Yes, it is crowded, but you just need to understand the patterns and be in the right place. There are some places I wouldn't want to live in SM. Just like any other area. There are some areas of Pasadena I wouldn't want to live either.
Given your price range you should look in west LA (lots of UCLA students live there, but it can be congested), Culver City, Palms, even down to Venice or Marina del Rey. You could also look east to West Hollywood (I find that even more congested and is further from the freeways - one reason I don't like Hollywood/HancockPark/K-town but that is a personal bias). As you move east of Culver City south of the 10 it begins to get cheaper but also sketchier. You can also look in Brentwood and Pacific Palisades but I doubt you'll find anything for $1400 except maybe a studio.
You'll need to seriously reset your expectations if you move to the westside wrt housing. Assume you'll pay double or triple for the equivalent size you have now.