I am going to be traveling around , (hotels , etc) and want to build or
buy a small as poss dipole for 40-10m.

Hi, Is it your intention to have the antenna inside the Hotel room? If it is,
I can tell you from experience that you will not have very good results. I
assume it is due to the amount of metal used in the building, especially the
newer ones. The best resuslts I have had operating from a Hotel is running
coax out to the pretty good mobile antenna mounted on my vehicle. This is not
always possible, for a number of reasons, but when you can, it is your best
bet.
If you could run a loaded vertical out a window, or mount it on a balcony.
You will have to use a counterpoise or radial wire with the verticals. If the
balcony is large enough you might be able to string a small loaded dipole.
When I did the above, the results were dissapointing. When I have tried
anything inside the room, the results were poor.
73 Gary N4AST