I've probably attended over 30 weddings over the years. Only at 1 - which specified "black tie" and the bride personally told me "everyone will be in gowns" - did I or any other wedding guest wear a full length gown.
Go for the 1st dress, but have a sweater or shrug handy in case the ceremony is inside a church or temple so you can cover yourself up a little.
Wear whatever dress makes you feel good. You can wear a long dress to a casual wedding. My aunt did that for her own sons wedding. I love both of the dresses that you have picked out. If the wedding is coming up or it's this summer then both dresses will work. You can wear a short dress to a evening wedding. My sister did that and she looked super cute. Pick the dress that you know for sure you will feel good in. I love them both,Groom Tuxedos
! Since, the wedding is in Rodeo Drive in Beverly Hills, then you want to look super cute. Even if your too dressed up it won't really matter. You're in Hollywood where eveyone cares about how they look and dress. The dresser you look the better.
It really depends on the type of wedding and dress code (which most put on the invite these days). If it is formal you can wear the long gown because that would be appropriate. If it is a more casual wedding then full length should be reserved for the bride and bridesmaids. If it's not on the invite give the bride a call and ask her what the dress code is .