On Saturday, September 29, 2018 at 11:06:55 AM UTC-5, DerbyDad03 wrote:

Am I nuts to be wondering if ...

No, you're not nuts, but your thinking is in the wrong direction.

Maybe with 2-3 adults it will flex on it's own even if fully glued and
bolted, but what if only one person is sitting on it?

Screw that idea. That ain't reality.

Am I, as usual, overthinking a simple project?

Yes. Don't alter the basic design of the bench in your pic, but improvise, here and there, and make yours better, than what's in that pic. The basic form/design will remain the same, but tweak some elements of the design, for a different purpose than sitting flat on the floor. Don't worry about it sitting flat on the floor.

Your daughter and her friends will be aware of the floor or furniture issue, and they don't care about that. Those issues can't be changed. Only some unknown SOB will walk in to someone's home and complain about someone's furniture or floor. In turn, your daughter should tell them to sit on the GD floor... or leave!

Okay, your daughter wants that bench! Really? Might she want it better, but not realize it. *I don't know, but might she want something very similar to it. You've shown us, before, that she has a distinct taste for rustic furniture, so she just might want something exactly like that, but I'm suspecting a slight improvement would be more desirable. Soooo.....

I'll go out on a limb with some bold(?) suggestions....
I just got back from a week's vacation (it's 8 PM, now, a little late in the evening), so I need a little more time for explanations and to gather some pics. I have several similar benches that I think would help with your decision.... and with some design element alterations to your linked bench. I think your daughter may like some of these altered design elements, while keeping in mind she likes (and wants to maintain?) the basic plain-Jane look and basic design of the bench.

Personally, I can see the bench in that link has an issue, or two, that are not desirable.... especially for a dining table bench.

I'll post, again, tomorrow.

Sonny