I tend to dress for comfort or practicality vs. fashion when travelling. Wearing jewelry, high heels, a watch, or clothes that don't breathe well aren't worth their drawbacks.
For long overnight trips, I've started wearing/carrying layers for the inflight cold temps, as well as a sports bra vs underwire for comfort (helps get through security sometimes too). Closed toe shoes are a must also.
If I'm going to look tired when I arrive, who cares what I'm wearing.....