Hi booknerd,
Thanks for letting us know what you ended up deciding … and congratulations on your new mattress 
As you know I think you made a great quality/value choice and I’m looking forward to your comments and feedback once you’ve received it and have had the chance to sleep on it for a bit.
There is some good information about sheets and bedding in post #7 here and the other posts and sources of information it links to that may be helpful.
Phoenix