Kids of all ages can ride the miniature trains of Largo Central Railroad the first weekend of the month. 


From their site:

The Largo Central Railroad (LCRR), founded in 1991, was built and
is now maintained through the work and dedication of the LCRR club
members and through generous donations from the people of Largo,
Florida. We currently have approximately 1.2 miles of main line track
with numerous passing sidings running through beautifully landscaped
Largo Central Park. Public runs are held on the first full weekend of
each month. Second and fourth weekends are “FUN Run” weekends
for members and associate members.Third weekends are work weekends.
Fifth weekends are mini-meet weekends.  If you have any questions,
contact us at (727) 585-9835. Membership in the Largo Central is open
to anyone with interest in large-scale model railroading and the hobby
of live steam.