Themed campaigns are what piques my interest for Gestalt.
The campaign is all about righteous wrath and smiting the wicked: Gestalt with Paladin
The campaign is all about a sudden wild surge of arcane magic in the world and people are beginning to manifest without training: Gestalt with Sorceror.
The campaign has a metatheme dealing with the power of the mind: Gestalt with Psion - Or with Psychic if you are using GR's Psychic's Handbook.
The campaign is about a barbarian tribe making it's way into civilized territories: Gestalt with Barbarian.
You get the idea!
Anyway, Edena the concept of Gestalt looks powerful on the surface, but it really isn't. It is more versatile and possibly more powerful, but not on the scale you seem to be thinking. Remember that you only get the better BAB, you only get the better saves, you only get the better # of skills. The only real stacking you get is with spellcasting and class features. It isn't even a straight out equation for twice as many options or being twice as tough.
A strong Gestalt combination will try to shore up weaknesses. As an example, you might try to be sure you end up with three good saves, decent skills, and a strong BAB. If you were going to focus on playing a gestalt wizard, you might think about pairing up with one of the fighting classes. But Paladin and Fighter are actually less appealing because both classes favor heavy armor, which you don't wear as an arcane spellcaster. The Barbarian is a nice option, it shores up your fort save, gets you great HD and is a strong BAB option. It also has more skill points than a wizard. On the other hand, the primary class ability of Raging cannot be coupled with your spellcasting. The Ranger, on the other hand, will shore up your Fort & Ref saves. The HD aren't as strong, but you have even more skill points. An Animal Companion could give you a personal bodyguard to help keep people from harassing your spellcasting. The eventual Evasion is pretty tasty as well. As well, you get a modicum of low level divine spells. The improved BAB makes your ray spells, and other ranged touch attacks, very successful.
A weaker Gestalt Build doesn't shore up weaknesses, it just layers on abilities. An example would a Gestalt BarbarianFighter. In this case, maybe you wanted to play a Barbarian and wanted the bonus fighter feats. There is some strength there, but you still suffer from poor will saves.
Gestalt characters are interesting because they do give you more options. But they don't necessarily give you a great deal more power. As has been mentioned before, no matter what you still only get one action/round.