My buddy has the 5 w/GPS. When you combine it with a lakemap chip it's a really sweet set-up for ice fishing as you can pinpoint spots on lakes and mark your location for the next time you're out. I don't know anything about the sonar vs. flasher issue or if there is a slight delay. All I know is I want one.
Also, there are down imaging and side imaging versions available, and ones with and without GPS. Be sure you take that into consideration when you're shopping. I've gotten excited about some pretty good deals I've seen on the Helix 5, only to realize it doesn't have GPS. If you're going to use your for ice fishing I think you would want the GPS version.
Whenever I want to take a kid out fishing and keep them entertained, then I always go to Kelly Dudley. In the summer, it is impossible not to catch a steady stream of sunfish. I have never tried it in the winter, but suspect it would be a good place to keep an eight year old busy.
If you go out, make absolutely sure to bring ice cleats.
There is an indoor fish camp going on in Faribault this weekend. http://www.maxsolutionsonline.com/cityoffaribault/Customer/ActivityDetail.aspx
Are you looking for this summer?
Are you looking for cabin type resorts, camping, tent/RV?
Here is a place to start:
I live in the area so haven't spent to much time at different resorts but I've always liked R&D Resort on Straight Lake in Osage, MN which is only 8 miles from Park Rapids. Isle O' Dreams is another very cool place to stay.