British Airways Denver to Luxembourg is as low as $394 round trip and $424 to Brussels using AARP discount link. AARP membership currently costs $12 and is not age restricted.
Delta/SkyTeam Airlines have fares around $20 to $60 more.
Icelandair Denver to Amsterdam is $490 round trip and available for Thanksgiving week travel. Denver to Brussels is $409. Icelandair tickets can be planned with a stopover in Iceland for about $20 more.
Travel departure dates are October 22 to early December.
British Airways AARP discount ticket
Denver DEN – London LHR – Luxembourg LUX – London LHR (overnight) – Denver DEN
$394.06 round trip Sat Oct 21 – Sat Oct 28
British Airways AARP discount ticket
Denver DEN – London LHR – Brussels BRU – London LHR – Denver DEN
$423.71 round trip Sat Oct 21 – Sat Nov 4
Delta Airlines ticket with Atlanta 22 hour layover outbound
Denver DEN – Atlanta ATL (8pm-6pm layover) – Brussels BRU – Atlanta ATL – Denver DEN
$441.36 round trip Sat Oct 21 – Sat Nov 4
Icelandair ticket Denver to Amsterdam Thanksgiving week
Denver DEN – Keflavik KEF – Amsterdam AMS – Keflavik KEF – Denver DEN
$490.37 round trip Sun Nov 19 – Mon Nov 27
