If you don't wan't something larger than your current 24", but are willing to budget up to $1000, Dell's 24" 4K monitor
is currently at $850. You'll need a lot of graphics horsepower to run at native resolution in more demanding games, but it should be great for photo editing work. However, as with most IPS (or IGZO) panels, input lag isn't going to be the best. However, if you are not a serious/competitive twitch gamer, I find concerns about input lag to be somewhat over-emphasized. I have a later revision Dell u3011 (30" IPS) and don't notice input lag when gaming.
If you are willing to move up to something larger, then I suggest waiting for good price on an HP or Dell 30". Yes, the 27" 1440p monitors are cheaper, but you loose the 16:10 aspect ration that you currently are used to on your 24". You should be able to find a 30" from a good brand for ~$1000 if you have a bit of patience (the Dell u3014 was $1000 on the last Dell days of deals)