To make the house bigger...or not??

I've mentioned before that our neighbors are rich. They both work as pilots for American Airlines and don't have children. They are VERY nice people and that's why I like them.
They are sweet to our children (letting Megan ride Ginus). They smile and wave whenever we see them.
They have given us things and helped out our landscaping project with their big tractor. I return the favor by cooking a nice meal. Wayne loves my chicken pot pie.
Wayne just had back surgery.
Before he went into the hospital, he had a new jacquzi tub installed in his bathroom. Well, his house is only 3 years old. He gave us his old jacquzi bathtub (which is a very nice tub). Wayne needed a specific tub that had a jet in just the right place for his back.
"Thanks!" we said in deep appreciation.

There's just one problem. It won't fit. Our bathroom is too small. So we did some thinking...

How about a remodel?
Rates are so low right now. We have tons of equity. Our house payment would only go up not even a hundred dollars to get 60 thousand.
We could extend the end of the house by 12 feet to increase the size of 2 bedrooms, 2 bathrooms, the downstairs playroom and create a stairway access to that room.

The whole idea got my head spinning...dreaming.
But I hate the idea of upping our debt. The way we are going right now, we could have our home paid off by the time the girls are going off to college.
But it would increase our home value. We DON'T plan on leaving.

I know, time to make a pros/cons list.
Right now the pros are lookin pretty good!

Somehow I knew that "free" tub was going to cost us! This is NOT a do-it-yourself kind of project. Unless of course, I hired my dad.

My dad can do anything.