We had a cal king and it was a PIA to find bedding. I would go with the King, after your eye gets used to it, you won't miss those 4 inches at all. We dropped sizes from a Cal King to a Queen now THAT was an adjustment, but I love being able to stay warmer at night and the bonus is bedding is less expensive. Rule of thumb, function over form. If it will work better for you, go with the king.

I like all of your upholstered choices shown. I think they will work nicely with your desk and do have an elegant feel, although I've always been partial to iron beds. If you're still looking at iron beds I can recommend Charles P Rogers. Great customer service and my daybed is high quality with a beautiful hand painted finish, much like the antique iron bed I have in DD"s room. I had a Wesley Allen and have seen RH beds - all nice but they don't seem to be as heavy and sturdy as my Charles P Rogers bed. Another iron bed company I'm interested in is Brass Beds of Virginia but I haven't seen those in person.

Check out Wayfair... they have lots of platform beds.

I looked in your Ideabook to see if I could get a sense of colors and styles you like but looks like you really like gray and white. Since your room is very neutral, you can go in different color directions. To get us started I think since the rug will be more visual than the bedding (except pillows) to keep things simple I thought we'd start by looking for a rug. Navy is very versatile and can go with different styles and many other colors. Tell us what you think of this rug - pattern and color. Here is the link so you can see more photos https://www.rugsusa.com/rugsusa/rugs/rugs-usa-banded-tribal/Navy/200BDBD03A-8010.html?adpos=1o25&creative=198870395426&matchtype=&network=g&device=c&mkwid=fgXthIRl_pcrid_198870395426_pkw__pmt__pdv_c_slid__product_200BDBD03A-8010_pgrid_46044902634_ptaid_pla-323238385428_&pgrid=46044902634&ptaid=pla-323238385428&cl_a=click&cl_aid=rugsusa&cl_asid=adwords&cl_ch=sem&cl_vend=adwords&cl_camp=847468994&cl_adg=46044902634&cl_crtv=198870395426&cl_kw=&cl_pos=1o25&cl_mt=&cl_gtid=pla-323238385428&cl_id=CjwKCAjwx_boBRA9EiwA4kIELvV1vwt7aLAA4tHVDiSWJ3bvqZMZd2Iq7DOeZZAP0TNibptcfIyd-hoCXeUQAvD_BwE&cl_cache=4569587778767373615&gclid=CjwKCAjwx_boBRA9EiwA4kIELvV1vwt7aLAA4tHVDiSWJ3bvqZMZd2Iq7DOeZZAP0TNibptcfIyd-hoCXeUQAvD_BwE