GU24? Blech. Isn't that a California thing?
Yep. Yet another way the State tries to herd us citizens into their way of thinking.
Personally, I'd tear those sockets out and replace them with good ol' E26 ones... And while I was at it, I'd put in 4 of them if I wanted more light.
The adapters are all over ebay and elsewhere. They really don't add much to the length of the bulb.
That said, my patio lights use GU24 CFLs. The Feit BPESL 23TM/GU24 (2700K, 23w, 1600 lumen, 90 CRI) is a decent choice. It is about 4" long, so should fit wherever a A19 would fit. The other ones I have are the MaxLite MLS26GU (2700K, 26w, 1650 lumen, 84 CRI). These are a bit bigger than the Feit at about 4.5" long.
As these CFLs burn out, I will be switching to adapters with LED bulbs. More light with less power. Also the GU24 versions of the CFLs are a lot more expensive than the Edison versions - which further makes the case for LED.