Phoenix Dactylifera Seedlings:

These have been great. I got them to germinate in early June. Then they were neglected for a while in soil that was probably too soggy and dense. Even though it was a cold start to the summer (lows in the lower 50s, highs in the 60s), the seedlings kept on growing. I now have 6 solid seedlings that I'll transplant soon. Each one is over 6 inches tall.
Adonidia Merrilli Seedlings:
The first set of seeds I got were too old and didn't germinate. In late August, I ordered some seeds off of ebay that were very fresh (don't be afraid to contact the seller and ask about the age of the seeds). I got a nearly 100% germination rate in about 2 weeks. These seedlings are a little over 2 months old right now and aren't that big, but they only just emerged from the soil recently. Right now I have about 20 seedlings.
Washingonia Seedlings:
These are what I started out with in May. I have 13 seedlings that are steadily growing. Next spring, I think I'll plant some in the ground in a somewhat warmer and drier part of the yard and see what happens (with a little bit of winter protection for sure). The winters aren't usually that cold here, but it's the once-a-year or so frosts with temperatures in the lower 20s that I would have to watch out for.