May I ask advice about SIM cards for iPad Pro and iPhone.

May I ask advice about SIM cards for iPad Pro and iPhone. We are having two weeks in the Canadian Rockies and three weeks in Alaska wilderness lodges. How much data for iPad (Google maps etc plus email) and which carriers. Would we need different SIMs for USA and Canada? Many thanks in anticipation.

I'm not sure about Canada, but in the USA the carrier with the best coverage is AT&T. There are outlets everywhere and they have data only plans that will suit you! You can get monthly plans that can be topped up easily online! Be the "nice friendly Aussie" in the store and the staff will cut SIM cards and set your device up for you! 

i used AT&T last year and  they were on the whole very good to deal with.

I went to one of there Company stores and  ten minutes later i was up and running.

From memory  their plans were called Go Phone

You could get something from www.usaprepaidsimcard.com.au as they work in both the USA and  Canada, but their website does state: "You must initially use your sim card in the USA to be able to thereafter use it in Canada and Mexico. The sim card will not work if you are flying directly to Canada or Mexico, and will only start working when you arrive in the USA."

I haven't had to purchase a sim card in Canada, but my friend here who is from Canada said it can be a kerfuffle and the plans are compartively expensive (he swoons over the Amaysim unlimited plans).

As Trevor says above, AT&T will have the best coverage and the best compatibility for your iPhone and iPad.

You might also want to check out getting a monthly wi-fi plan from Boingo.com which roams onto many "paid" wi-fi networks (even sometimes paid hotel networks).  You pay something like $10USD for the month and get unlimited wi-fi.

In terms of how much data, that's really "how long is a piece of string".