Figure out your Pico vs Killington plan before you arrive, not after - they are very different days out and treating them as interchangeable is a mistake. Pico for a quieter, more old-school experience. Killington when you want more terrain, more vertical, more noise at the end of the day. Mixing them across a multi-day stay is the move. Ask staff at breakfast which mountain is skiing better that morning. Not Google. Staff. Because they actually went yesterday.
Make dinner reservations before you need them - ski season weekends fill up fast at the better spots and after a long day on the mountain you really, really dont want to drive around looking for a table with dead legs and low blood sugar. Staff can recommend specific places and some will call ahead if you ask nicely. Worth asking!
Foliage timing in Vermont is genuinely hard to predict - shifts by a week or 2 depending on the year and no one can tell you exactly when until its already happening. If thats your main reason for coming, book a flexible rate and keep an eye on the Vermont foliage tracker in the weeks before. Peak color around Rutland usually lands early to mid october... usually.
Pack for real Vermont winter cold. Not city cold - mountain cold. Proper base layers, not just a tshirt under your jacket. Layers that actually do something. Hand warmers in your pocket as a default not an afterthought. The wind on the mountain is a different category from what most people are used to and there is gonna be at least one person this ski season who learns this on day one and spends the rest of the trip buying stuff at the resort shop at resort prices. Dont be that person.
Hot tub after the slopes, before dinner - thats the window and its worth protecting. Earlier evening before the dinner crowd gathers means more space, quieter water, sometimes the whole thing to yourself. Small detail... but after a big mountain day it is genuinely one of the better parts of the trip and its worth timing right rather than just wandering down whenever.