If your current inner ring is a 30, then I would recommend changing it to a 26-tooth, not a 24-tooth as suggested above. Compared to a 24-tooth, the 26 tooth will make shifts between them slightly smoother, make the cadence change slightly less, and will wear out slightly slower (go for a steel inner ring for touring). Also, make sure that you have a chain retention device mounted inside the inner ring to avoid losing the chain off the inside of the ring when down-shifting (N-Gear Jumpstop is a good model). I'd simply do this for now, and leave the cassette and RD alone unless after rising a bit you feel you still need something lower.