Going to test ride a Surly LHT tomorrow and I know zero about touring bikes. Looking at a Surly due to great recommendations on this forum!

What should I look for in a touring bike? I will be using it for errands in town (grocery shopping, etc.) and will be doing some touring with DH this summer (not camping - he camped out enough in Vietnam). I want something that can handle a decent load of groceries but still be comfortable. I definitely want a steel bike.

All advice will be greatly appreciated!