As others have said, triple is your friend. I use it with 9- and 10-speed cassettes, even ('80s Trek tourers for me). It lets the rear gear set be tighter for all the benefits that tighter ratios bring, while easily providing a 1:1 ratio or sub-1:1 ratio. You get the additional aesthetic benefits of a triple on a tourer as it looks the part. I also like that the 26-28t small ring handles the slow/hard stuff, which allows the big ring to be 52-53t to handle all the downhill speed fun. I enjoy my dessert after eating vegetables. Plus, on 65cm+ frames like I ride, a 53t big ring gives a proportional look, which I appreciate.
You can geek out on the gear ratio calculators, and I have before, but a 52/39/28 up front and 13-28 6- or 7-speed freewheel out back (or very similar) should set you up for a lot of success. 8-speed indexing chain from SRAM or someone will work well.