Dropsync will let you select and sync multiple entire folders/subfolders to your Dropbox instead of files only like the Dropbox app. FX File Explorer, ES File and others will let you select and copy/paste multiple folders/subfolders or files to/from Dropbox. However, selection must be done item by item. AFAIK Android and iOS do not have an equivilent to shift+ or ctrl+ for multi-select. My Nokia N900 is the only phone I've used that does.