I've stayed in several of their hostels, which I mentioned in a PM. But it's interesting that they currently required an active membership for US stays or charge $3 per day otherwise. I paid my $18 for the membership but at this point I'm not sure I'm going back before that membership expires. I only managed to stay 2 days, but I suppose it goes to a good cause.
I did stay at the HI Los Angeles Santa Monica Hostel just after Christmas and it was very nice. It was remodeled specifically as a hostel and it was probably the nicest hostel I've ever stayed at. My room was recently painted and the bathrooms looked as if they were remodeled recently. The breakfast areas looked pretty new. My criticism was their zero alcohol policy, which seems odd compared to most hostels (including one where they actually had a nighttime social with liquor and beer served). They showed me rules that said a guest could be asked to leave (without a refund) if found with alcohol in the room or common areas, even if not consumed on premises. I had to figure out what to do with my 50 ml bottle of Glenlivet 18, which was the only alcohol I had with me when I checked in. They theoretically could have held onto it at the front desk.
It was just about a block away from the LA Metro Santa Monica (yellow line) station and when I got to LA Union Station it took less than an hour to get there.