I'm afraid Allie is right about bettas and gouramis.
Since you're keen on having the betta, maybe a couple of female bettas instead of gouramis? Their fins are much shorter, but still can be colorful and are in the size range you want. Someone else suggested this in a species only tank -- would it work with a community tank, or would it just make the betta more aggressive?
Just wanted to add, as far as hardiness goes, neons are definitely not the ones to cycle with. From what I have heard, you may want to add them in 6 months when the tank is mature. I've found corys to be reasonably hardy, but the owner of my fish store seems to feel that the young ones are delicate, so you might want them a little bigger (just don't get the smallest ones)
And yet, glow-lites might be the ones to cycle with -- smaller and less taxing to the bio-culture, also less expensive to replace than cory cats.
I'm not sure about hardiness with bettas, but they are always adults when they are sold and therefore will produce more waste, so I would add them after things are more established, especially since they might be aggressive with others (adding them later might help with that.)
So I would say: glow-lights first, then cory cats, bettas, then neons. JMO.