I would go with the 36mm Datejust- and if possible, a vintage one for the dome crystal. Datejust is a classic design and gentleman dress watch after all, so 36mm is just nice, IMHO. For a bigger dial size, I'll look at the sportier offerings from Rolex such as the Submariner and SD 4000. Just my 2 sen.
Here's my vintage 1601 from the 70s saying "Hi!"

