Hi Scott.
I like that you reached out to your audience to solicit suggestions.
There have been good ideas presented. You may also consider a "make an offer" section of the website. That can help purge older inventory while still allowing you to negotiate.
Mixing it up always helps - a previous poster suggested running a special on MTH engines one week, then perhaps Lionel Rolling Stock (or even more specific "Hoppers". A sale directed at either RCS switches or maybe Signals of any sort would also be good attention getters resulting in people buying more once on your website.
Most important - keep up the great work, reputation alone accounts for more sales than I think anyone realizes.
Last, tell your team they are doing a good job - it makes them want to do even better if your words are sincere.
Sorry for the ramble but many years in sales and marketing will do that to a person...
Paul