This sounds like a cruise, as these two places are among the popular cruise routes.
I don't know about Cabo, but we visited PV many years ago; We spent a week there, taking local transportation as much as we can to get a feel of the local life.
It is as Americanized as you can get for foreign soil. All the natives speak adequate English, they even accept US dollars (probably because the exchange rate was 10 to 1 that time, making it extremely easy but I do recall some venders have calculators stand-by), so you probably don't need any Pesos. There is a Walmart. Apparently some Americans are making a winter home/long stay there. Weather wise, it is very tropical; the air is warm and moist in contrast to our dry weather. We did get a feeling the local people have a lot of respect for their golden goose, in other words the crime rate is low as they want to earn your business 'honestly'. Maybe it changed in recent years.
Two other things I like to mention:
1. Be prepared to haggle. The price is not fixed and there is a lot of room for negotiation. With so many shops around you should be able to find a good deal if you have the time and patience. 50% off from the original sticker price is not uncommon.
2. Be prepared to be harassed by the mobile street vendors. They will swarm you as IHO indicated. But in general if you refuse politely they will go away
If you do visit as part of a cruise, most of the above don't really apply as the time on the shore will be limited.