I'm currently selling my Potter 19 and have moved up to a "new" (to us) Seaward 26RK. I dearly love the Potter and how forgiving it was when I was teaching people to sail. I'll miss that boat. The Seaward has the advantage of being able to spend much more time aboard, we plan to sail for a month or two at a time. The Potter is a great daysailer or for a long weekend. There are many for sale at all price points depending on age and upgrades/equipment.
Having the direct experience, right now, of moving from a tolerant 19 footer to a complex 26 footer, I can 100% agree with all the posts here. Do not start with a large complex boat. There is an interesting line in the Seaward owner's manual that says something like, 'this boat is more complicated than a home.' That's true, it is also more complex than most RVs. And, as noted above, you can get killed with a big boat. A little boat (or a home or RV) is much less likely to kill you.
I've also sailed many other boats up to 61 foot monohulls and 44 foot cats, the forces on these larger boats can be sobering. Fun boats, but you cannot trailer them and I want a trailer-sailer. More to your particular case, when learning it is fun to be able to take your trailered boat anywhere your heart desires, including calm lakes and bays as you experiment with your new vessel.