Post # 1
Our wedding is going to be on a Sunday and is a wedding that 90% of our guests will have to travel to. To make it fun for people, we plan on going horseback-riding/doing some spa treatments at our venue on Saturday, the day before the wedding. Unfortunately, we can’t host the horseback-riding or spa-going but we want to invite people to come along. What’s the best wording (just for a wedding website) to inform people that this stuff will be going on but that we aren’t paying for it?
Post # 3
I would avoid phrases like "you are invited" and add a note about the cost to each event description. You could say, "If you wish you may join us at the spa at noon on Saturday. The cost for this is $45, payable by cash or credit card."
Post # 4
I agree with snmcdowell. I wouldn’t say "you are invited" because that implies you are hosting and might lead to some confusion about who pays and who makes reservations, etc.
You could say something like:
"The groom and friends will be horseback riding at XYZ Farms on Saturday at 2pm. If you would like to join him (which he hopes you will!), you can find info on prices, directions, and reservations. at their website (www.XYZFarm.com) or call 1800XYZFARM."
and repeat for the spa.