Domain Cycling Premium Bike Gel Seat Cushion Cover 10.5"x7" Most Comfortable Bicycle Saddle Pad for Spin Class or Outdoor Biking https://smile.amazon.com/dp/B08HDPPT38/ref=cm_sw_r_cp_api_fabc_BAwUFbMHPXEQV?_encoding=UTF8&psc=1
I have this seat and love it. It washes well in the washing machine
Poundo board. $16.99. I've had mine for 2 years.
The seatpost is a standard 27.2 post. I'm 6' 2" so I got a long 400mm one.
The saddle is always a tough (individual) thing. I have several from my mountain bikes but the upright riding style of the RR+ didn't work well with any of them. I got two different large plush saddles from amazon and returned one.
Here is the saddle I am using and is in the photo:
I have this one from Weaver - https://www.amazon.com/Weaver-Leather-00068-Round-Knife/dp/B00UVBJQX0 It's nice and solid and the steel seems to be pretty high quality. It will also require considerably less work to bring it to proper sharpness and has the benefit of a completely round blade profile, so jigs can be made to sharpen it.