As bad as it is, I always think of gifts in terms of opportunity cost. People generally have a preset amount they are going to spend, so you want to maximize the value they get for your benefit as well. If I ask for a game that is $60 that's a lot of other games (opportunities) that you're shutting out.
I generally try to pick things that I don't expect to go down in price much in the future (like game hardware, controllers, limited editions, etc), or I pick gifts that are universally cheap and I would buy them myself at that price . Since I wouldn't buy most games at full price, I don't generally ask for full price games, when I could ask for multiple cheap games. All of the people shopping for me aren't cheapassgamers like me, so they are probably going to buy gifts at full price regardless of what I ask for.
Lately I've been pointing my mom to some of the deals on amazon, or I add something to my amazon wish list with a price that she should look to spend. That way she knows a good price and doesn't get ripped off.
I'm much better at finding deals myself, so I do like getting gift cards, but I generally hate the idea of gift cards, dedicating a set amount of money to one particular store. It's a huge racket for stores, because many of them go unclaimed. Plus when some stores are going out of business a lot of them have stopped accepting gift cards during the close out clearance.