From Salida you will take 285 north to 24/285 junction just south of Buena Vista for the most part parallels the Arkansas river its pretty but nothing fantastic. Staying on 24 you will continue heading north towards Leadville. Leadville may be historic but it is an ugly ol mining town in a pretty setting. Nice mountains along with plenty of mines which in January you probably will not see due to the snow coverage. Just north of Leadville US 24 heads northwest to I-70 the road while fine gets narrower and can be a challenge in a snowstorm and especially if Vail Pass on I-70 is closed (it happens more than you would think but not that often). Which increases the traffic load substantially and all the idiot drivers in bad conditions. It is a pretty road. Depending on your travel plans if headed east on I-70 once you hit it you might opt to take HWY 91. It will take you over good road (it is also pretty) down to I-70 and you will come out at Copper Mountain Mountain Ski Resort thereby saving you some miles and going up and over Vail Pass. If headed west on I-70 then 24 is the way to go.
As far as things to do in the middle of winter you have skiing at Cooper (just north of Leadville small resort), skiing at Vail, skiing at Copper Mountian, skiing at Breckenridge, skiing at Keystone or skiing at Loveland Pass and all that goes with large modern ski resort areas (except Loveland). You could also find cross country skiing and snowshoeing if you wanted in the area. You could find without much trouble some snowmobiling rentals. As well as ice fishing at Antero lake, Turquoise Lake, Twin Lakes to name a few. If you are an avid flyfisherman some brave the winter waters to fish the Arkansas river in winter. Leadville has a nice mining muesem. Buena Vista has a couple good restaraunts. Leadville has a couple as well.
I am somewhat familiar with the area if you have specific questions ask away will do my best. Anything specific you are looking for, direction of travel, staying in one area a while or just passing through???? I think member Fkovalski (or something like that) lives up in the Silverthorne/Dillon area he may be a good resource for info.
Not sure what you mean by "break in the weather for 30 days" as there is no break in the weather up there in January (not that it snows everyday), it will be cold up high. Leadville is at 10,000 feet probably be lucky to hit 25 degrees on a sunny day, could be cold and clear one morning and a blizzrad 3 hours later.