Both are fairly close to one another. The W is in a more residential area (close to the local Uni) with Trader Joe's, Best Buy, restos, etc within walking distance. The SLS is across from Beverly Center so it's in a more heavy traffic area.

I thought the SLS was an all-suite hotel, actually, so you might look further into what a SNA gets you. I've stayed at the W and was given a pretty large 2-bedroom suite.

Both are fine hotels and it really comes down to what you're looking for.