My girlfriend got one of these, Ruger 22/45 with a 4.5 inch barrel, for her first pistol. Then she bought a VPD surplus Beretta 9mm and loves that. Now she is talking about AR-15 in 9mm

eek

or maybe a Beretta Cx4 in 9mm... so go figure. The Ruger 22/45 is a nice little accurate gun. It might be frustrating for your GF to learn to disassemble and re-assemble it though, as it is quite tricky at first. Eventually you get it though.
Myself... I always beat the drum for the Walther P22 and the SIG Mosquito, because I have had so much fun with these guns. These are mine. The P22 has been modifed by a gunsmith to have the shortest barrel legally available to me. The SIG has a threaded barrel (cap on in the picture), which is the only one that can be imported into Canada. Both are keepers.
On the left handed issue, I find the slide lock on the Ruger to be a bit weird, especially if you are used to service calibre pistols. It's the notch that is further ahead. The one in the rear is the safety. The mag release seems like it would be reversable, but the safety and slide lock are not.
The P22 has the (USP/P99-style) mag release which is on both sides. The (PPK-style) safety is also on both sides.
The safety on the SIG is the same as the P22. The mag release seems like it would be reversible, but you might need some parts that don't come with the gun. I've had the mag release apart on my gun, but I've never tried to put it back together on the other side. It might work.
For more on the Walther and the SIG, have a look at this thread:
http://www.canadiangunnutz.com/forum/showthread.php?t=132068