For appearance, particularly if she finds stock Android bland, try MIUI Android (or MIUI US) as they both offer English translations of the Chinese overhauled rom MIUI. It will also feel at home for her, with elements of iOS there and it is much more polished (including the messaging app). If you want stability, use the RC versions (not the weekly betas). I use MIUI Android myself, and I think their stable is 2.3.4a or something, but I use the weeklies. Keep the stock kernel, or maybe try Jame Bond for CM7/MIUI/Any for stability. Also note that MIUI Android offers deodexed Chinese versions, so you must flash the miuiandroid-ns_1.7.22.zip (or similar) first, then the ENPACK one (English pack or something).
That's about it for appearance, stability only I recommend Oxygen by Adam Green except its very much stock looks. I highly recommend you let her try MIUI though. Remember to wipe everything before switching roms, I'm sure you know about that. If needed use Titanium Backup to save your apps (seeing as you're already on CM7) and then restore them in MIUI, just remember only backup and restore user apps, not system.
Good luck, just ask here if you need more help
Sent from my Nexus S using RootzWiki Forums
Edit: Damn, beaten to it

can't type fast on my Nexus