Whenever I play with my wife, I play with a 6 copper 4 estate deck and don't tell her. This works as long as you don't draw a 4-estate hand on turn 1 or 2 (which luckily hasn't happened yet). She doesnt' really notice that I start either 2/4 or 3/3, maybe one day she will.
I actually find that to be quite fun, because it forces you do odd things. I'm sure you wouldn't be surprised to know just how rough a handicap it is to have a 6/4 starting deck.
The other option I like to do is just go slighly higher terminal-heavy so that I collide more. She doesn't really notice, but the games are a lot closer. Also, if Chapel is out, I don't buy it. I bought it once just to show her how good it is, and absolutely crushed her. She said she doesn't like throwing her cards in the trash (pretty funny). She'll only get trashers like remodel (trash for benefit).
I also play with my 5-year old, who LOVES witch. We put witch in every game he plays, and I make sure I never buy one. It is actually extremely hard to win (even against my 5-year old!!) when he's the only one witching. So the other option is to just identify the best strategy, then choose something else. I.e. always take a whacky deck.
I did a Kingscourt/Pawn deck the other day. I thought it would be whacky, and it ended up just being really f'king solid. I was totally surprised how strong it was. You tend to learn new things by taking the road-less-traveled now and then.