I'm using the D16 often, good small tip, 1.6mm is actuall not big :), but you can get the D12 or D08 also.
For throughole i often use D24, sometimes D32 (quick soldering of pinheaders)
The various C/CF tips is supposed to be fine for dragsoldering
This hakko can use both T18 and 900M tips, they are exactly the same tips, I would by this kit:http://www.ebay.com/itm/10-x-Solder-Scr ... 0788095725
the are clones, works just fine, maybe hakko originals are better, but first someone needs to start carry them.