skip the vouchers. i'm a big fan of cheapair.com---they accept bitcoin payments directly with BTCPayServer:
https://www.cheapair.com/blog/update-on-our-search-for-a-new-bitcoin-payment-processor/they've been accepting BTC since 2013 and they are a genuinely thoughtful and pro-bitcoin company with good customer support. they even have dedicated phone/email support just for crypto customers!
so i like to support them even though their prices tend to be a bit higher (~2-8%) than expedia. they are
sometimes competitive but on average expedia definitely undercuts them.
Cheapair doesn't list many budget airlines in Europe so they're effectively pointless for Europeans unless they're going long haul. Budget airlines are usually 2-5x cheaper than the obscurities Cheapair throws up and are vastly more numerous in the times and routes offered.
And I still don't see why anyone should be paying a premium for the honour of spending BTC. On checking one flight there, London to Boston, Cheapair are $50 more for the exact same flight.
maybe things are different in the states. i've seen fare differences that were pretty negligible.
it's not just for the "honor" of spending BTC either. cheapair is an awesome company that genuinely does right by its customers. expedia is the polar opposite---they fuck people over left and right, are misleading about prices and hidden charges, and they have horribly unfair refund policies. their online reviews make it very clear who i would rather deal with:
if you've ever been fucked over by expedia (i have been), you won't mind paying a few % higher to use cheapair. it's worth it for the smoother experience and peace of mind.
that they are huge bitcoin supporters, use BTCPayServer instead of bitpay, and have dedicated crypto customer support is just icing on the cake.