in your case, outland definitely. Especially if you're planning to move in 1 to 2 years. Inland process can only be started once you're both in Canada, and woudn't allow your wife to travel in and out.
get familiar with the forms, and see what is needed. THe process takes about 1 year, if you factor in the time to gather all the proofs and prepare the application, and the different stages. It can be done faster than that, but it really depends. It's in your interest to start early, so you avoid the stress of waiting for the PR to come through.
However, in your case, as you've lived all your life in the US as far as I understand, you will have to prove that you are serious in moving to Canada. So it might be worth to start investigating a little bit: where you will live, what you will do for a living etc, so that when you fill out the application, you can show that you are indeed moving to Canada. You will need to convince CIC of that, and as I suppose your links to Canada are not very strong for now, you can work on that.
Get familiar with the forms, and start gathering proofs, but don't fill out the forms just yet - as they might change between now and when you apply.
Good luck,
Sweden