Excerpting...
However, the return has us changing carriers in Houston - Continental from Bonaire and then United to Calgary. The layover is 2 hours to do US Customs and then security. I know it's tight, but is it doable? We often travel through Toronto internationally and I wouldn't be concerned there with a two hour layover.
Could anyone give me some of their "sage" wisdom?
I'm not a Houston local but have been thru that humongous airport a few times, and I got curious here...
I take it that you are flying non-stop Bonaire to Houston IAH on a Saturday? CO1899 arriving at 11:24 am? I think you will actually arrive in Terminal E, but D & E are both adjacent to the International Arrivals Building where you will clear Customs and Immigration to the extent a thru International passenger will - since you are not actually arriving into the US but just passing thru a US airport.
But if I am correct on your Continental arrival at 11:34 am, the next United or Air Canada flight to YYC/Calgary seems to be at 2:35 pm/14:35 hours - 3 hours later; United #511 or AC #5689 - does that sound right? It goes to Denver where you connect to the flight to Calgary arriving there at 8:52 pm/20:52 hours, correct?
Whether a 2 or 3 hour layover, you should be fine for the terminal change and check-in, I think - but it does seem to be a little tricky. On the attached map, you'll see that you will take the Terminal Link - a large, elevated car - from the International Arrivals Building to Terminal B, then walk around the inside of that square building to catch the bus at gate 67 to Terminal A.
BTW, United or Air Canada should recheck your luggage at the International Arrivals Building, so you won't have to worry about getting it up and down with the Terminal Link or onto the bus in B67.