I've been drawing deckplans for Traveller starships since the mid-80s; my style of late has been heavily influenced by Rob Caswell's deckplans for Digest Group Publications.
These deckplans were all produced with Adobe Illustrator, using a symbol library that I've developed.
The title font is URW Globe Heavy, and the label font is Helvetica in various weights.
The 1.5m grid uses 1/4" squares (i.e. 1:236); the table below shows the scale if an A4 plan is printed on larger A-series paper.