Mine

MapsWeLove = {"map1","map2","map3"} --Put any maps but atleast 2, else it's pointless to do random.
HoursToWait = math.Rand(1.8,2.1) --Hours to wait to switch (can be decimal ex. 1.2 hours)

timer.Simple(60*60*HourWait, function ()
	local tbl = table.Copy(MapsWeLove)
	local curMap = game.GetMap()
	for k, v in pairs(tbl) do
		if v == curMap then
			table.remove(tbl, k)
			break
		end
	end
	Msg("Server performing random map change...\n")
	game.ConsoleCommand("changelevel "..tbl[math.random(1,#tbl)].."\n")
end)