Take a look at past years' weather data from the closest weather station(s) to where you're going to be riding (similar elevation, etc) and think about what you'll need at those temps. Probably not too cold out there mostly. I wouldn't overthink it too much at first. Don't buy a bunch of expensive stuff before you go out a few times and really figure out what you need. Get by with the basics at first and then get some more advanced stuff. If you're sticking to resorts I wouldn't think you'd need super swanky gear. Wool sweaters work fine as mid layers, and can be gotten cheaply at Army Navy stores, for example. A lot depends on your own internal furnace, too. Get out and figure out how to keep yourself warm, because what other people need may be different from what you need. Personally, I burn pretty hot but have cold fingers and toes. You may be just the opposite, so take a lot of what people recommend with a grain of salt.
That said, if it was me I'd get uninsulated hardshell pants (more like mountaineering pants than rain pants) that will stand up to some abuse and can be worn in nasty weather all year. For cold days wear a thin base layer and a fleece "expedition weight" base layer or some kind of insulated liner pants over that and the shell pants on top. For a midlayer, probably the best thing I've ever bought is a Polartec Powerstretch 1/4 zip top. I got it about a month ago and it's gone with me everywhere since. Today it kept me fairly warm with just a cheap base layer and a goretex jacket at 0F with a wind chill of about -20F, but I don't overheat in it easily, either. A lightweight down or synthetic jacket is nice to have if you find yourself standing around outside getting cold frequently. Either size it to wear as a mid layer or to go over your shell, depending on what you prefer. I'd probably go with synthetic where you are, too - primaloft and thermic micro are both really good.