Originally Posted by
LondonElite
That's a bit much. Welcome to FT, but take it easy!
If you don't show for your first flight (ex-LGA in your example) the rest of your itinerary will be cancelled and you won't be getting on any flights. On the return, you can drop the last flight (to LGA in your example) without any consequences, unless you do it daily.
However, on the return your checked bags are going to LGA even if you don't. The exception would be if you go through customs at DFW and can just walk out with your bags there without needing to recheck them to get them to DTW baggage claim.