I am a big proponent of Surly bikes! I will say that after riding 26 inch wheels, 700c seems harsh and unforgiving. And if you're smaller, the bike looks like it fits better and isn't a franken-bike. I still have two 700 c bikes. But the Surly is stable dependable, I've loaded it down with 50 lbs of gear and it has never given out on me. My 520's stock aluminum rack broke, but they've since introduced a new style (that looks like Surly's nice rack, LOL!). The LHT with the right tires, rolls fast. The stock tires are a bit gummy for my taste, so I switched to one with lower rolling resistance and a fatter stance and never looked back.
Point being, it's the one bike purchase I've never regretted making. I don't think you would either. Surly's run big. So the 46cm, fits a little big for me at 5'3'' but thanks to my long torso it's perfect. 42cm probably would have been better, but that's the case with all of Surly's models. Keep that in mind during fitting. Forget what you "should" ride, and look for the best fit!!!
I've never ridden a Salsa Vaya, but I hear they're nice. The cross-check would be a good light tourer-commuter option. My Trek 520 has been lovely, but I've replaced so much stuff to make it a better touring-bike (including the rear cassette) that unless you're ready to do a lot of customizing or they've changed the specs dramatically, I couldn't recommend it. I know people have been telling them to change the gearing, brakes, etc, but the 520 continues to roll out the same each year. It will get you from here to there right out of the gate, but you may decide that changing some stuff suits you. The 1400.00 price tag is quite hefty for a bike you have to modify.
The LHT is spec'd well of the gate, imo. Choose a steel rack (aluminum ones don't handle heavy loads well) and roll off into the sunset.
If I could, I'd build myself a Soma and a Rivendell too. I basically love steel bikes. The LHT is a +1 for me.
"Things look different from the seat of a bike carrying a sleeping bag with a cold beer tucked inside." ~Jim Malusa
2009 Trek 520-Brooks B-17 Special in Antique Brown
2010 Surly Long Haul Trucker-Brooks B-17 Standard in Black
1983 Fuji Espree Single Speed-Brooks B17 British Racing Green