New Boat Shoping

[Cptn ahab]

I'm shopping for a new boat that i plan to buy next year. I've researched and looked at several brands. I plan on this boat lasting our family until the kids are grown, about 15-18 years. We currently are using a 1972 sidewinder speed boat that my wife grew up water skiing behind. I converted it to make it more fishing friendly. I'm thinking we would make the new one last. I found a dealer in Spearfish, SD they sell ranger and Lund. Seem to be honest and offer good service. Your opinion on BlackHawk Marine would be appreciated.
The ranger 620 and 621 make me drool, but never driving or riding in one have me skeptical of spending that kind of money. The only boat other than our boat I drove was a Lund rebel and tracker ski fish model, both boats were 17 foot range and 90 and 115 hp range. I was not impressed, the storage was great and live wells etc, but performance sucked. I would think the larger higher hp boats would be better but never had the opportunity to go in one. The dealers near me say its not possible to go out for test run but may be able to set up a ride with a friend.
We plan on pulling a tube and skiing using a "y" cradle around motor when the time to play comes, but the vast majority of time would be fishing. Not that interested in the crossover boats (reata etc ).
So what kind of performance, turning, handling waves, take off should i expect from a boat? What brand, style, etc do you suggest? I'm tilted pretty far towards the Ranger 621 with a 300 vrod.