Bumping this up. I think we've pretty much settled on Al Bustan Palace for 3 nights, followed by Alila Jabal Akhdar outside of Nizwa.
However, it looks like Anantara has just opened a new property to directly compete with the Alila.
http://jabal-akhdar.anantara.com/
Room rates are a bit higher, and don't include half-board. The property is somewhat bigger (~30 more rooms), and has 3 restaurants versus the 1 that Alila has.
The Anantara has just opened recently so I don't expect anyone to have visited it yet by now, and we'll be traveling in March, so I hope that any opening pains will be fixed by then.
The Alila is highly regarded here and elsewhere on the internet. Any reason to stray from this and try out the Anantara that I am missing? Having never stayed at either brand before, I'm shooting a bit in the dark here.