If an appealing downtown area is important to you, as you mention in your question, then Highland Park is a terrific choice. As you travel North from Chicago, Evanston has the largest downtown, followed by Highland Park (I don't like that fact that you have to pay to park in Evanston's downtown). But there are other factors to consider as you search among the various communities on the North Shore. I have lived on the North Shore my entire life and there are so many opportunities to consider.
Each community along the North Shore has a different look and feel. If you have children, you may want to check out the schools (they are all fairly top notch) to see if they have the types of programs or facilities that you want/need. Evanston, Wilmette and Glencoe have nicer beaches than Highland Park, while Highland Park is the home of Ravinia Music Festival.
Highland Park tends to have more homes available in every price range than Willmette and Glencoe. On the flip side, real estate taxes tend to be higher in Highland Park.
Other things to consider, depending on the age of your children, are things like day care, places of worship, before/after school care, park district facilities and programs, etc. There are links to all of the North Shore communities on my blog, and I also have a link to a web site that gives you test scores for the various schools. So you can get one-stop shopping for everything you want to know about the North Shore.
If you have any other questions about the North Shore, feel free to contact me directly: nancy@NancyKarp.com 847-226-5594