All three major alliances have Denver to Paris on sale from $433 to $446 round trip to April 6, and then slightly more to $480 to May 10. Icelandair is as low as $427 round trip. SkyTeam has several other regional airports in France priced in $400s. There is wide open availability across several months of dates from January to May with numerous airlines.
Amsterdam and Brussels are similar prices in $400s with three alliances. Manchester, Frankfurt, Munich and London are priced from low $500s to low $600s round trip.
As a California resident I find these Denver fares attractive in combination with the low round trip ticket prices from several California airports to Denver around $100 to $140. That means under $600 all-in to Paris from California.
These are similar deals seen two weeks ago for Denver to Paris. Loyalty Traveler – AA/DL/UA Denver to Paris $448, Amsterdam $444, many cities $431-$544 (Nov 10).
American Airlines Denver DEN – Dallas DFW – Paris CDG – Dallas DFW – Denver DEN
United Airlines ticket for all Lufthansa operated codeshare flights
Denver DEN – Munich MUC – Paris CDG – Munich MUC – Denver DEN
Delta Airlines Denver DEN – Minneapolis MSP – Paris CDG – Detroit DTW – Denver DEN