Well, I find that garrison defense ships are grouped on the bottom bar, along with you planet defense structures, while your fleet is grouped in the left bar. Its far from perfect, but for now it allows you select your fleet without selecting any of you garrison.
I'm on the edge of whether garrisons are over powered. I like the idea that garrisons can hold their own. However, 800 logistic (fully upgraded) points for a terran class world is a lot. Its nearly half the max fleet size. If you were playing defensively, keeping your fleet at your terran world, you'd be able to kick the butts of anyone invading your world. And this is before starbases are added.
On the other hand, its really expensive to bulk up your forces this way, and I think you need idle shipyards to build your garrisons. Also, you can't build this stuff at the start. You need to research techs to get the garrison slot option, and then you need to research even more techs to improve them (as I recall, they start at 100 logistic points per slot but eventually upgrade to 200 with the right techs).
