I think Candlewood is OK. The other similar brand I am familiar with is Marriott's Towneplace Suites (TPS). I say:
+ Candelwood: free laundry, beautiful bathroom in renovated properties, better bedding/towels
+ TPS: mini-breakfast, fully non-smoking, better lobby area
As a Platinum in both programs, I have gotten upgrades at TPS on point stays. I have never gotten any upgrade at Candlewood - paid or points.
I love the "dining table" and "desk" combination workbench type of thing at the Candlewood. I hate how tight the queen bed + sofa + nightstand are placed in the Candlewood studio. The bathroom of the newly renovated properties are great.
I think for longer term stays, Candlewood would probably be more pleasant because of the better bed and linen and great work area.