Wife visitng England for two three month periods?

[WoeIsMe!]

Having gone through literally every available option, this is what I've decided has to be done. I don't see any problem with this being able to happen, right? So, she wants to visit me from October-December, then go back to America for Christmas for a month, and then return February-April. She looked at getting the one year visa (which I believe means that you can come and go as much as possible UP TO SIX MONTHS without border problems) however the cost was too great to risk being turned down. This route would be free, wouldn't it, and considering the one month gap half way through no questions should be asked?
What sort of evidence would be necessary to grant these visas? Is it a case of bringing the evidence to border control one she arrives in the UK or what?
Also there shouldn't be any hassle with these two periods, right?
I'm cluless....

[Lucapooka]

Would you consider making all of your immigration questions in one single thread? This way, everyone will see what you already know and what you lack, and new questions will make sense in the context of what you have previously discussed.

[WoeIsMe!]

Well actually this is a totally distinct question so I thought I should post it in its relevant forum.