hanging a swing from a branch about 25-30 feet above

Who can you hire to do this? Has anyone done this?

I have. Tree company put it up when they were doing some trimming up there. 2 birds, one stone.

+1 for a tree company. They also install elaborate Christmas lights and other similar tasks.

You might also try a roofer, if you have a relationship with one, or even your gutter cleaning guy. Anyone with a big ladder.

Thanks! @lukeysboat --where did you find your swing. Seems hard to find one with such a long rope.

Atlas Ladder & Scaffolding in West Orange sells rope by the foot, and if your kids are of a certain age, and a certain turn of mind it's a great place to visit.

Assuming you can come up with the swing seat separately.

eta: http://atlasladder.com/construction-supplies/4349932

Fairly simple to toss a rope over a tree branch. Google toss a rope over a tree branch. Seats can be made yourself or purchased finished. I have done this many times by the "toss a weighted rope over a tree branch" method. Make sure you wear head protection.

Use a drone. (just kidding)

I tied a length of thin twine around a tennis ball and threw it over the branch and pulled it over the top. Then tie the twine to the heavier rope and pull it over the branch. I set up a simple rope swing and rope ladder using this technique.

jules867 - you can use any swing you would like and attach it to the rope. I bought a disk swing but I don't remember where from. Just be sure to use the right type of rope - synthetic is best for this application - I bought my rope in HD. It is the kind used for watersports and carries up to 350 pounds of weight. Also, be aware that from that height, your swing will swing far and wide. My kids now can swing over our fence and say hi to our neighbors ;-)

Also, our tree guys cut a piece of hose to wrap around the rope where it is tied to the tree to avoid it wearing out as fast...

Be cautious about rope strength and degradation of rope over time. I believe SO native, Elisabeth Shue, watched her brother plummet to earth, and die, on such a swing when the rope broke. My understanding is that this happened in Maine on a sheer dropoff. If you don't have a sheer dropoff then you probably have less risk.

See the following link for a reference to the tragedy of ES (and family) caused by breaking rope on a rope swing: http://www.indyeastend.com/Articles-i-2007-06-13-68291.113117-Elisabeth-Shue-Revisits-Her-Past.html

PS Consult with your insurance carrier to determine whether such a swing would be covered by your homeowner's policy. And, whether a fence would need to be constructed around the swing (to prevent others from being attracted to the swing and using it when you are not there).