I'm honestly in the same situation as you. I certainly don't want to go overboard with multiple card churns every 90 days or 6 months or whenever. I'm fine picking up a chunk of miles here and there to fund my one or two trips per year.

With that said, I've already gone overboard (in my own eyes).

I applied for the U.S. Airways card (40K miles after first charge, no annual fee for first year). Both for my wife and I. That one was easy.

Then, I applied for the Chase Sapphire Preferred for myself. $3K in 3 months. Not hard.

I kept reading and reading, and couldn't resist. I applied for both AA cards for both my wife and I. $4k and $1500 minimum spends in 6 months.

That is all I'm doing for the next year.

I should be able to make these minimum spends, and after I do my wife and I should both have 40K U.S. Airways miles, and 150K+ AA Miles, and I should have the 50K Chase Sapphire Points. That will be plenty of miles for us for the next two years. I plan on waiting until after I renegotiate these cards in 1 year until I sign up for anything else.