My list of creature comforts for work trips grew and grew! It makes such a difference.
Some of the things I found made it a bit more pleasant:
Be fussy about the hotel you stay in. I flat refuse to stay in a travelodge or premier inn these days - they are hit and miss, a tired one for three days is a form of torture. I even change my travel dates if necessary to work around this.
Check out locations when you book, I've been able to do a couple of work trips over the summer that have felt almost like a short break because of the location (and cost no more than any other hotel in the particular city).
Plan your evenings in advance, I've managed to have some nice evenings out at the theatre, lovely walks in parks, seaside walks etc - make the max of your free time. Ditch your colleagues too! If you know anyone in the area arrange to meet up with them.
Take enough chargers/cables etc
A good travel cup and your preferred teabags makes a difference
A change of shoes! So many people try to save space with just the one pair, somehow I find it comforting to be able to change my shoes of an evening!
Laundry sheets and a travel washing line is so very useful
Get some folding travel hangers, so many hotels there aren't enough, it's a small hit wildly annoying thing!
If you want to wash your hair take your own dryer, hotel ones are so hit and miss
Definitely a pen!
Take a shower cap