It depends on what is on these areas now. If this is stained and finished wood then use a good varnish as the finish. If these areas are painted then you can use either an oil base or latex paint as long as things are properly prepared.
Some more information is needed before any specific recommendations can be given.
– What is the finish on these area right now?
– Do you plan on stripping or otherwise repairing these areas?
Also a photo or two would be nice.