More PSP/Vita titles. Now, granted, I don't give my PSP the love it deserves, and I don't yet own a Vita, but I've seen a couple of titles show up for them both, albeit few and far between. (Probably more true for the PSP. I haven't paid much attention to Vita games on Plus, so I may not have noticed many that
have been posted.)
Other than that, I don't really care much. If I want a game enough, I'll buy it, and probably on disc (provided it's available). PS+ already offers free full-game trials, which I think is sufficient for just letting people try games out before deciding whether or not to buy them. I look at these free games as more of a little perk once in a while. Not really sitting around, hoping for specific titles to show up among the free games.
Sales that give PS+ members additional discounts, on the other hand... I'd like to see plenty more of this.
I've already gotten a handful of nice deals from PS+, including some of my PS1/2 Classics. I mostly stick to digital-only games when it comes to buying anything through PSN, which I personally feel are sometimes priced higher than they should be, so such discounts are a nice way of convincing me to buy those games, haha. At the moment, though, I can't think of any that I'm waiting for sales on... The last two I was waiting on were Okami HD and THPS HD, which, amusingly enough, went on sale one shortly after the other a couple months back. (Although I think I had just purchased Okami HD right before it went on sale, heh. Just my luck.) ...Then again, I have been waiting for such a sale for Fatal Frame III (PS2 Classic). I picked up the first two on sale not long ago, but the third wasn't included in the sale, so I'd still like to grab that one for a little cheaper.