I have a question about re-applying for cards later on down the line, and being eligible for the sign up bonuses. I am thinking more long term, like over multiple years. I've just started traveling a lot the past two years, and over the past few months have gotten hooked on the miles and points game. Other than my AMEX PR Gold, I don't have any rewards card. My wife is an AU on that, and doesn't have any rewards card of her own. Both of us have good income and good credit around 800. Just about all our spending currently goes on the AMEX, about $3k-$4k per month, so meeting minimum spends shouldn't be an issue.

Right now I am trying to come up with a good long term strategy and am curious about my options. Here's some things that have come to mind:

1. If you get a card with a big sign up bonus and then cancel it later that year, do you get locked out of future big sign up bonuses? I'm thinking longer time frame, like 1 or 2 years. For example I get the AA Citi, get the 75k miles, then cancel the card 9 months later. Can you apply for the card again for some future bonus (i.e. immediately, couple months later, year later, couple years later, never)?
2. If you get a card with a big sign up bonus issued by bank (chase, citi, amex, etc), will this prevent or hinder you in getting a big sign up bonus with a different card issued by the same bank? For example getting the AMEX PR Gold for 75k points, and then the AMEX Plat for 100k points?
3. For question 2, about cards issued by the same bank, but giving bonuses into different programs: should I be applying for them on the same day? Does it matter?

Like I said before, I'm looking at more of a longer time horizon of churning, focusing only on the large sign up bonuses and canceling the cards before the annual fees. Would we be able to do this on, say, an annual basis? Or are we going to get locked out of the big sign up bonuses once we receive them? I do travel moderately for work (15-20 domestic trips per year) so I'm able to top off FF or hotel accounts accordingly and get entry status on 1-2 airlines and hotel chains.

Right now getting hundreds of thousands of points spread around a couple FF or hotel accounts is very enticing. But if it's a one time thing, and everything after that would just be earned on spend or small promotions then it loses some of it's luster. And my wife is definitely not big on these strategies, but if it leads to tpac or tatl first/bus flights and nice hotel stays she might be a convert.

I've really loved the info I find on FT, and am starting to maximize my travel. Already in the past few months I've fast tracked to HHonors Gold, got 60k bonus AMEX points, utilized the DL 100k transfer for 50% bonus and silver status, have 10k+ bonus points into UA and HHonors with various rental car/hotel promotions.