Iron Horseman: I agree with you about sticking to a time period, B U T ...............
My model railroad time period is the late 1970s and I targeted that specifically. Why? Regarding engines and cars my time period is basically from 1938 to 1978 [for interchange purposes railcars are limited to 40 years of life unless heavily upgraded.] And the locos (steam and diesel) used during this time frame were many and varied. So, I have a plethora of engines and cars I can purchase (doggone it

) and stay in my time period.
And when on ebay I can easily say, "Wow that's a really cool car/engine/etc, and it would fit right in." Then I have to remind myself, "Where are you going to put it?" (This usually helps, but not always.)
Not only do I run trains but I kinda sorta collect the cars and engines too, and I enjoy changing the freight trains' consists a few cars at a time. (By the way, am I the only nut-case that does that?)
Anyway, I've liked trains from around age 2 (1949) when (I've been told) my Grandma would help my Mom by taking me (the oldest) then me and my brother for a walk every day, and the main line of the MoPac between St. Louis and Little Rock was 1 block away. (I saw some steam locos go by but don't remember them.) Plus there were two active spurs/side tracks right there also. That was in the Missouri Ozarks, 6 miles from the highest point in MO, Taum Sauk Mountain.
I'll share one quick memory of that time. When I was older, whenever a freight train stopped to switch one or both of the spur tracks, I'd jump on my bicycle and go down and watch. The way the spurs left the mainline was to the south, so the trains were always north-bound, which means the track grade was still down-hill from Tip Top Mountain. After the switching was done by the head and rear brakemen, the rear brakeman would wait for the caboose to come by and run and jump on. Many, many times I thought the train was going too fast, but I never saw any of the brakemen miss catching that caboose.
DougC