I run a 60" Mimaki solvent and its all i've ever needed.
anything 54"+ is highly recommended, I assume your Boss wants to print MDO graphics... 48" won't cut it, I usually print an extra 1" border around everything for trim or wrapping edges (waterproof'd construction signage), and everyone who prints knows how big of a pain it is to try to print edge to edge all the time.
UV printer would be sweet someday, but 30k vs. 100k made the decision a hell of a lot easier to go with solvent for our first printer. 5years and still kickin' ass!
Latex printer from HP is also a new thing. No need for an exhaust/airfilter, since it only emits water vapor as opposed to solvent printers' noxious fumes.
roland, mimaki, hp, epson are great printers to look into in general.
contact your
sign suppliers and they'll usually let you demo a floor model. have some cool files handy for them to rip/print for ya when you go to visit.
also, if you can hold out til next spring before your purchase... if you can manage to attend the ISA
sign convention, most distributors'll knock around $8k off the sticker price as a
sign show discount. Free vacation! AND you get to see EVERY printer worth knowing about.