Bring your own chair/towel

I think it would work fine. My brother did the same for his distillery wedding. He said “bring your own folding lawn chair” but we brought about a dozen extra for the older family members who either wouldn’t remember or couldn’t carry chairs out themselves. There were still people standing but no one seemed to mind since it was a short ceremony.

Are You Having A Reception Afterward? If So Make Sure You Have Somewhere They Can Leave Their Chairs/Towels So Guests Won't Have To Carry Them Around Or Worry About Them. Other Then That I Think Itll Work!

View Quoted Comment Yes we will have a garage at the house with a pool and lots of lounge chairs.

I think this is a little strange. It sounds like your guests will likely be traveling; What if bringing a beach chair is not an option? I think renting chairs for your guests is a better option.

View Quoted Comment We are looking for something simple. Most guests will be commuting about 2.5 hours but we will be accommodating their lodging too. I figured 15 minutes in a beach chair in front of our rented mansion isn’t too much too ask, right? Haha

I would opt to do outdoor throw pillows and you provide the chairs for the seniors

If I were a guest at your wedding it wouldn't bother me to bring my own chair, I would just do it because it's a simple request lol

I think I prefer the blanket and pillow idea. Maybe you could get a few tapestries and pillows in your wedding colors and lay them on the sand, along with chairs for anyone that needs one. I think that would be super casual but a bit more romantic.

If your guests are coming from 2.5 hours away, I would provide chairs. That's a long drive. What happens if they forget their chair? They can't run home to get it. The ceremony itself may be short, but for guests, they may be standing and waiting around. Maybe you can borrow lawn chairs from local friends?

That's a pretty long way to travel to request people bring their own chairs... especially if there will be drinking going on at your reception. People will likely forget chairs or have to leave them at the venue if they use a ride-share service to get home. They aren't super expensive (chairs, blankets/towels, etc.). I'd just cover it as the bride/groom.

Edit: didn't see your note about accommodations being at the venue. Will that be for everyone invited?

The last wedding we were invited to asked us to bring our own chairs and I thought it was a bizarre request. We don't own folding chairs and we didn't want to purchase them for the occasion. We did not attend because the wedding in general sounded like a lot of work and we weren't especially close to the couple. Though, to be fair, they also asked us to bring our own food and drink also. So the chair thing alone wouldn't have been a deal breaker.

I had long wanted a "potluck picnic" wedding where everyone brought their own blanket and some food to share, but I think that definitely only works if people are local (which many of our guests are not). I think BYO towel is awesome for an intimate beach wedding with close friends and family, but I wonder if people will want to sit down on the ground in fancy dresses and other clothes, and if the ceremony is short, people might be more comfortable standing. Also I don't have a big enough, nice enough towel that I would want to bring to a wedding and sit down on in a fancy dress. It would be awkward to a have a mix of people standing, sitting on the ground, and sitting in chairs, so I would just caution you to consider how that would work.

If your ceremony is no more than 20 minutes I would probably just have people stand and have chairs available to those who need it.