Is this a home office or commercial office?
Abiu would be a good choice, makes an attractive tree even when not fruiting, also would consider a sapodilla, canistel, macadamia, longan, white sapote, wampee.
IF this is a commercial office, visible to patients coming and going, I would tend to stay away from anything deciduous such as annona, mulberry, etc. (I know some people are weird with respects to eye appeal). Also, if its commercial, make sure there are no municipal restrictions and/or requirements that would limit/dictate your choices.