I am in the process of levelling a druid alt that i intent to be Bear/Boomkin. I am having trouble figuring out the best way to handle my actionbars when I change spec. Right now I use Bartender but it seems to save keybindings to specific slots per bar. I need pretty different bar setups for each spec and stances and I am at a loss how best to configure. On my warrior it's a bit easier as I tend to use similar abilities in my tanking and dps specs/stances so that I can keep mostly the same binds. My bear/boom is only in the 50s and I can already see this won't be the case.
What I do is have dual spec and then use one of the specs for balance/resto and one for cat/bear. That makes it easier to organize. I'd be interested to see if anyone has a better solution though.
Possibly switch to the default UI until you hit 85. At 85 you will have all your spells so each time you switch specs it will essentially be the same. I don't exactly understand fully what your problem is, but I play Boomkin/Bear on default UI and have no problem with it.
get any bar addon, then add all possible keybindingd you want to have (before you put the spells on the bar) keep in mind that you have to put your bear cat boomkin tree and flight form on your action bars aswell, because they swap possition if you change spec (your "class bar") this way you have the same buttons on bouth way, and you only need to put the spells out once and never have to rebind a key when you respecc.