Wow! Talk about timing! I just finished loading some recent pictures onto photobucket so I could answer a similar question from a PM. My travertine deck was installed July 2015, and I waited until now to decide if I wanted to enhance and seal or just seal. Time slipped away, and my decisive tendencies are extremely slow.
I did a lot of research on sealers, but keep in mind I'm not very technical minded or handy as a DIYer. Dry Treat seems to be the best by far. Adding an enhancer was a bit trickier (can't remember why). I couldn't afford a local company certified to apply the Dry Treat to get their great warranty. (about $3,000 for materials and labor for approximately 700sf of deck) And, they want a 3 week dry period for curing - very difficult to predict and ensure that here in Houston. Finally I chose Enrich N Seal by Aqua Mix. It was recommended by a TFP member from the Houston area - I had read many of his posts and liked his thinking. (ie - he seemed smarter than me which may not be a huge rec!). The only place I found it around here was at Home Depot (luckily). It was on Amazon but more costly than Home Depot. On the instructions, Aqua Mix says : Ready for surface traffic in 12 hours; keep dry for 12 hours; achieves full cure in 48 hours. It did rain after about 24-30 hours. The rain beaded up beautifully. My son and a buddy put the sealer on - just one coat (that was about all the work I could squeeze out of them, and they were even handsomely paid!!! Kids.....). For the 700 sf, it took them about 4 hours including a couple of short breaks and quick bite of pizza. One brushed on the sealer, and the other guy followed right behind wiping off the excess (within 5 minutes to prevent hazing). It brushes on super easy (I did the samples the night before). You can also use a sponge, paint pad, or sprayer. It seemed to me the brush would waste the least. For wiping any excess off, my son liked larger pieces of t-shirts, or whole t-shirts. We used almost 4 bottles of the 24oz size.
This was done recently, March 27th, so I don't have experience to share about how it holds up. So far, we love it. It looks great, and we've had about 3 big rains just since it was sealed - all beaded up. I haven't found it slippery, but I probably wouldn't run on it. For me, I felt the same on the before sealed stones - I have a metal hip and don't take any chances running. My son says it is still not slippery. Below are some before and after pictures.
This BEFORE photo was taken about 8 months after the deck was installed. No sealer/enhancer.
I took this picture today. In person, some of the greater contrasts in the photo just aren't obvious in person. The darks aren't as dark and lights not as light - just my camera I guess. But the enhancer/sealer really brings out the gorgeous patterns in the travertine. The travertine deck/patio is a mix of Noche and Classic (a light crème) in the tumbled pavers. My coping is the Classic filled and honed.
Good luck!
Suz
