If you want a steel frame make sure it says chrome moly main frame, not just chrome moly seat tube.
Cheap bikes usually say something like "High tensile steel" which means cheap steel.
I don't have a problem with lugless chrome moly frames-more an aesthetic thing than anything else.
Lots of older MTBs with 26" wheels make good, sturdy city bikes.You can get fairly skinny tires for them-trek 800,820,930,950 etc are mtbs and all but the 800's always seem to have full chrome Moly frames(some of the 800 have "seat tube" chrome moly just so they can say chrome moly.)

If you like aluminum just look for decent components/wheels. Decent components usually means good frame.
Luck
Charlie
ps since the weather is getting colder this is a good time to start looking-late spring is a bad time since folks are thinking about riding again.Take your time-there is ALWAYS another deal out there.Don't try to get too great a deal-you'll see lots of folks bragging about the great deal they got-yeah, but they spend there whole life looking,and never twel you about their not so good deals.Once you find what you like-fair price-offer 80%-and work up.Be polite-don't say "it needs this, or it is scratched" just say "nice bike, will you take x amount?"