Scanning can't correct certain errors best handled at the time of the shot itself, outdoor over-reaction to UV being one of them. A true warming filter, ever so slight like a KR1.5, would be overkill for Ektachrome unless the sky were overcast and the subject matter a bit too blueish due to that. In fact, I would never leave a filter in place without a specific reason for it. I have em all : no.0 colorless Hoya UV filter (which worked best for high altitude UV per se with the immediate predecessor film, E100G), a 2B Sylight, 81A,B, and C, B&W KR1.5 and 2.0 (a little redder than the 81 series), the Singh-Ray KN, a Tiffen equivalent to a 1B and 81B combined, and an 05 cc M filter. No - I don't carry around all these at the same time! Most are only for sake of fine-tuning specific color temp issues characteristics to Ektar CN film and its own functional predecessor, Portra VC. I'd probably just leave em all home if shooting Ektachrome except perhaps the 1B and an 81A, which address entirely different issues.
Polarizers are like sugar and cream in coffee. Not for me. Spoils the signature flavor. Didymium filters? - poor man's Fauxtoshop. Cheap filters rather than reliable multicoated glass ones? - why bother?