Well, the DAZ 3 piece suit does have options for different lapels, single breast or double breasted, plus options for different collars on the shirt (just in case you want to do a tux).  I haven't seen any other suits with these extra options.  Plus there's one texture add-on at DAZ (Saville Row) and a nice one at Poser Pro's as well.

I've had the ones for David and M3 the longest, so those are the one's I primarily use. You could use any, but most are limiteed in style and textures.

Most "dressy" shorts seem to fall into the cargo short variety, but most have material options to hide the outside pockets. You could alternatively create a transmap for the dress pants. 

The attached image is a converted suit (D3) converted to Apollo, along with David's cargo shorts and stockings from DAZ's 19th Century Suit, Men's Dress shoes (available at DAZ as well). Or if you have a Poserworld subscription, you could use the Wizard school uniform, convert Laura's shorts and socks/shoes (of the Jschool socks/shoes, which have a modelled cuff). 

Just mix and match until you find the style needed. 

I doubt anyone is going to make a set. Seems to be lost in the "historical" sub-genre, this style of boy's suits. When I asked Steve at Poserworld to make a scout uniform, he opted for the more current style, instead of the traditional 30-50's style (worn until the late 1970's; there are still a few branches that wear them today, though). 

-- Jeff