We are considering replacing our wood windows and shutters, some of which are taking too much annual maintenance time? Any suggestions?

I've had a chance to review our decision last year to install wooden shutters (approx 2.5 cm thick) and treat them with teak oil (brand name "Teak Wonder") rather than paint them. Do it twice a year.
For information you can check-http://thewindowoutfitters.com/
Wood Shutters bring warmth, enduring beauty and richness to any room and can be defined as furniture for your windows. They are great from the outside as they do inside your home.

Any wood windows and shutters are going to take a lot of maintenance. You could spend more money on better finishes but it would still take a lot of work to keep up. Really if the time for maintenance is the issue I would go with metal windows and synthetic shutters.

If you choose to continue with wood then for paint I would use Duration from Sherwin Williams and if it's a clear finish use Epifanes spar varnish.

Replacement windows are a huge business. There are a couple different types. Replacement windows are made specifically for your existing openings. Your old sash get removed and replaced. In most cases, no additional work is needed for interior and exterior trim, it doesn't get touched. The most common replacement windows are for double hung style windows. You didn't say what type of windows you have.

The most common and inexpensive replacements are vinyl. Normally, there are local companies that make these type of replacements. They'll come out and measure your existing windows. Larger window manufacturers also make replacement windows and you can get wood sash if you prefer and in numerous "looks". Companies like Anderson, Marvin, etc. offer replacements, custom made for your house.

Completely replacing your windows will involve a lot of work since interior and exterior trim, along with the entire window and frame get taken out. This is the most expensive and time consuming way to go. New windows may not fit the exiting framing and you are often looking at a complete house paint job, in and out.