RIJimmy,
I may be a year or two ahead of you in this, having recently become a boat fisherman after years on the beach with two small kids (1 & 4). Here are some of my experiences.
Start smaller. I nearly jumped into a new 22' walkaround but instead chose a used 18' CC. With little kids, the boat is one of many activities for the family and often not an option given the weather (boat size irrelevant). Therefore, usage is limited. My wife and I decided that we didn't want to spend so much on the boat that it would make us feel as if we HAD to use it all the time. As it turns out my 4 yr old still doesn't like to go fast, limiting what we can enjoyably do as a family. We do alot of slow trips to the beach, making the shallow draft and easy handling of the 18' a benefit.
Also with a smaller boat, you learn a lot in a more manageable package. I can trailer, launch and load single handed, easily. Not to say I can't do a larger boat, but the 18' is easy. It will cost less up front and to use/maintain. My 130HP sips fuel compared to a 225HP. Learning to maneuver, dock, etc. in a smaller boat is easier.
I'm not too badly limited in my range. Because of the family obligations, I don't get many opportunities to take 8 hrs and go fishing. On the days I do, I am looking for good weather with relatively calm seas. I would run from the south shore to PTown in my boat on those days, and know that I could get back safely. Not looking to go to BI, a different animal. A 22' would certainly make a rough trip home easier, but I can do it.
I catch fewer fish from the boat. After years of learning how to catch fish on the beach, I have to start over in the boat. I spend more time operating the boat than I do fishing. Techniques are different, equipment different, locations, etc. Fishing now highly dependent on weather, wind, where from the beach you don't think about it as much other than how the conditions influence the fish.
I spend more time on boating issues, navigation, safety, maintenance, maneuvering, while OTHERS fish. I don't mind as I love boating as much as fishing, its just different.
My plan, for what its worth, is to keep it fun for the kids now by staying in calm water, short runs, fishing for schoolies (make sure they catch), and not stretching the limits. When my young one hits 4-5, we'll likely move to something larger to extend things.
On the other hand, if you can get away regularly without the family and have the disposable $$ for the extra expense of the the larger boat, forget everything I just said and go for a 25' CC with twins.
