If you haven't done so already, now is a good time for you and your significant other to make out your "life documents" - at a minimum - wills, power of attorneys (if you become disabled) and health care proxies (a/k/a DNR's), with a local attorney.
If you have a specific individual or individuals who want your train stuff then put a paragraph in your will about who gets it and a provision of what happens to it if that person should predecease you. A typical provision might be, "I hereby give, devise and bequeath my entire model train collection, including but not limited to locomotives, rolling stock, accessories, electronics, scenery and trackage, to my _______________, Mr. __________________________, to be his absolutely and forever. In the event that the said __________________ shall predecease me, I direct that said collection shall be left to ______________________." Just make sure you speak with the individual(s) beforehand to make sure they want the collection. Nothing worse than leaving something to someone who doesn't want it.
In the alternative, you could put, "I hereby direct, as soon after my decease as possible, that my executor/personal representative sell my entire model train collection, including but not limited to locomotives, rolling stock, accessories, electronics, scenery and trackage, on the open market for any amount reasonably obtainable and that the proceeds therefrom be distributed in equal shares to my children, ____________________ and _______________________. My executor/personal representative may use the services of a broker, agent, auction house, hobby store or any other reasonable means with which to liquidate said collection."
The language is limitless, but if you don't put anything specific in your will about how you want your train collection disposed of, at least put a paragraph in your will that states, "I may leave a Memorandum stating my wishes with respect to the disposition of certain items or articles of tangible personal property. Such Memorandum, however, will be simply an expression of my wishes and shall not create any trust or obligation, nor shall it be offered for probate as part of this Will." And then write out a memo of what you want done with your trains and keep it with the will.
Hope this helps and Lee, just in case, what's your wife's name ?