I really can't give you any direct experience with the .32 ACP, but can give you the heads up that your new firearm selection may be limited, and your ammo price/selection might get a tad on the interesting side.
For the most part, the .32 ACP gets relegated to pocket pistols. That said, Bersa does make (or has made) the Thunder in .32 ACP, but it's hard to find. There's also, of course, the Walther PPK in .32 ACP, but be prepared to part with some cash if you find one.
Re the Thunder .22LR, I have shot one but never owned one. Have had a couple of the .380s. I found 'em a fun little range gun, but I think there are better options for carry.
That said, if you want an alloy- or steel-framed .22LR semiauto with a bit of heft to it, the Thunder is one way to go and it won't break the bank.
If you want to get into a similar gun for around $350 to $450, Walther does make the PPK and PPK/s in .22LR.
Another option, if you can get into the $400-plus range in .22 pistols, might be the Ruger MK IV line. The MK IV is a proven design but with some nice, user-friendly upgrades over its predecessors. And you can get one in particularly any configuration you desire. I have a Mk III in the safe, yet I'm still sorely tempted to pick up a IV.
Also in the $400 and up range is the Browning Buckmark, another good pistol available in many configurations.
In the synthetic-framed .22LR semiauto pistols, I'm rather drawn to the S&W M&P Compact. Perhaps worth checking one out.
Last bit: .22 autoloading pistols can be picky about ammo. If you do go .22LR, I'd start out with something with a bit of velocity like the CCI Minimag. I also like the Aguilla Super Extra.
Have fun looking around.