Hi bill,
I'll poke my nose in here and suggest the following:

You can start with either the 16 or 18 series, but I would go with the 18 series. Disadvantages to doing that are the 18 series does not have any real small pin count options (like 8pin), and older books won't cover them as well.

Some chips I like:
18F4620 (40pin) or 18F2620 (28pin) - Has most of the available hardware functions (I2C, SPI, A2D, USART, Etc), loads of memory, and runs at 32MHz on the internal clock.

18F4550 (40pin) or 18F2550 (28pin) - Similar to the above, but with USB support if you want to dive into that.

Others will have their own preferences. A parametric search on Microchip's site will turn up a lot of options. Selecting the functions (like USART) you can't live without, memory size, pin count, and such will narrow the field nicely.

You'll find lot's of help here, especially if you put the work in on your side.
All the best as you start learning. Welcome!
SteveB