You will need to be looking at the 31 ft Class C.
Coming from your spacious Class A IMHO you will NOT be happy with a 24 ft. I.E. corner bed and real small bathroom limited amount of storage bays.
The 31 or some call it a 29 will give you a queen walk around bed. And many offer the split bathroom which gives you the spacious and tall glass surround shower with skylight. And more storage bays.
Don't know if they still offer a basement model but again you will be happier with one. On my Four Winds it offers a real sewage bay like an A.
I have a Four Winds 31ft basement model split bathroom. And it gives you a very open feeling from front to back. Many of my friends with A's say it looks more spacious than their A does. Especially the ones with the layout that has small hallways.
I know you are partial to the Winnebago but my friends that have a Winnie 31 ft Class C say mine has a much better layout with more room.
So, that all said take the time to check out the "Four Winds" line. You will find the layouts much more user friendly and more spacious which would make your transition easier. And 'numerous' models to choose from.
Don't know what engine your A has but I am now a firm believer and advocate for the Ford V10, power that never lets you down especially if your are towing a toad!
And you will be surprised how much nicer the handling and driving is on a Class C.
Hope you find the just right MH for your family. :C