LOL I must be deficient, because I still don't understand what you mean by applying LA "to both sides".
[Edit: "... Now we make them gestalt Barbarian/Clerics. Fred gets to add 10 levels of cleric. If George's LA applies on both sides, he gets to add 5 levels of cleric. I don't see how, if we started with two characters of the same power, adding 10 levels of cleric to one will balance with adding 5 levels of cleric to the other." -- I think this made me Get It. It really is a dicey situation... my upcoming campaign is going to be a high-powered one, so I'm sure I can just ignore "balance".

]
I should point out that, for this particular campaign, most of the races have LA. There is going to be a Gnoll, a Drow, a Duergar, and a Goblin. While the Gobin doesn't have LA, he'll have three strong friends and an animal companion to boot.
I've decided to do option "A". My first level will be "Gnoll"//Bard (or Rogue); my second level will be "Gnoll"//Barbarian. I'm sure this works from a mechanical standpoint... well, mostly sure.

This solution works for the Gnoll because he starts with 2 levels of humanoid. For Drow etc, I'm sure it works differently...
So, if I've read correctly, a Drow Sorcerer//Favored Soul 2 is functionally a level 4 character, but gets no extraneous increases in BAB, saves etc. for his +2 LA in levels "before" taking class levels.
The Gnoll Barbarian//Bard (or Rogue) gets 2 levels of "Gnoll" before he starts gaining class levels, but only has a LA of +1. If I'm still figuring this correctly, he would have to be a Brb//Brd 1 in order to "balance" with the Drow;
level 1: Drow//Drow Gnoll//Gnoll (LA +1 on each)
level 2: Drow//Drow Gnoll//Gnoll 1 (LA +1 Drow, 1 HD of "gnoll")
level 3: Sorc//FvSl 1 Gnoll//Gnoll 2 (2nd HD for "gnoll")
level 4: Sorc//FvSl 2 Barb//Bard 1
As the DM, I'm pretty sure Gestalting one level with each level of the Gnoll class works... otherwise, I'd have to keep the Gnoll without class levels in order to stay "balanced" with the other level 2's, even if the drow has a +2 LA to the gnoll's +1.
I'm pretty sure I'm making this more complicated than this has to be, but at least I feel like I'm using my head for more than pr0n and video games. *LOL*