Taking photos during travel to enlarge to 16x20

I'm a beginning photographer and never plan to be a pro, but I would like to preserve our motorcycle trips well and use some of the photos as artwork in our home. I also have 2 grandchildren that I would like to photograph well. I'm not into video much. I find that we look at pictures much more than movies. I currently use a 10mp Canon Powershot and have done enlargements up to 8x10 and they were excellent. I hear from some sources that megapixels should not be the deciding factor, but I honestly don't know anything about about all the other stuff (sensors, etc.) I would also like recommendations regarding lenses for shooting wide angle shots and macro lenses (I think that is the right term for taking pictures of things like a ladybug sitting on a flower petal.) I'm heading to the Badlands this summer and would really like to take a good camera. Also, I am considering purchasing a refurbished model directly from Canon so I can get more for my money. Any recommendations would be greatly appreciated!