Unless you have a burning desire to see Vegas,I wouldn't drive there just for a flight home. i'm sure you can find good flights from Los Angeles to London. Also do research on the cost of a one way car rental. There cn be a hefty additional fee.

For a 20 day trip…

This is early fir mountain driving where some roads aren’t yet oprn. Thry open late May- October/ novrmber.

For rough drive times/ a,ousts.

1 day Seattle to Portland or oregon coast

2-3 days for olympic Peninsula

3 days oregon coast

2 days for California coast north of San Francisco

3 days for coast between

1 day drive to vegas

Addition drive time to go inland and back.

It’s about 10+ days driving thrn times sering spots

1 day Seattle

1 day Portland/ Columbia gorge

2 days San rancisco

3 days LA/ San Diego

1 day vegas

That's 8 days seeing citues.

8 days seeing+ 10 days driving+ 2 days flights is 20 days.

In May you might get better flight+ rental car prices reversing direction flying into vegas then ending in Seattle

Yosemite valley is peak waterfall time in late May but I didn’t include thst. It woukd take about 3 days going there, seeing it, back to coast.

Doing death valley would add a day on the San Diego to vegas drive from 1 to 2 days.

You can easily do a full 3 weeks just in California/ vegas loop. You can easily do a 3 week washington, oregon loop trip.

A 3 week califirnua loop would look like

Day 1 fly to vegas

Day 2 egas

Day 3 to Death Valley

Day 4 to Fresno

Day 5 to Yosemite

Day 6 Yosemite

Day 7 Yosemite to napa

Day 8 to SF

Day 9-10 SF

Day 11-13 to LA

Day 14-17 LA and San Diego

Day 18 to Joshua tree

Day 19 to Grand Canyon

Day 21 Grand Canyon

Day 23 back to vegas and fly home

For Washington/ oregon

Day 1 fly to Seattle

Day 2-4 Olympic

Day 5-7 oregon coadt

Day 8 redwoods in extreme Northern California

Day 9 redwoods to Medford

Day 10 Medford to bend via crater lake

Day 11 bend to Columbia gorge

Day 12 Columbia gorge to Portland

Day 13 Columbia to mt rainier

Day 14 mt rainier to seatyle

Day15-16 Seattle

With those extra days you can go up to Vancouver or Victoria or San Juan islands for a few days.snd mt baker/ bnorth cascades area

You could fly into San Francisco. We started a 2-week road trip from SF years ago. You don't need a car in SF.

SFO - SF (3-4 n) - {pick up rental car before you leave SF} Yosemite (3 n) - Monterey (1-2 n) - Central Coast / Pismo Beach (1 n) - L.A. (3-4 n) - Anaheim (? n) - San Diego (3 n) - South Rim Grand Canyon NP (1 n, maybe) - Las Vegas (? n) - LAS

Thanks, everyone! The message I'm getting is that Seattle all the way to San Diego requires way more time. In 3 weeks max. is it that impossible?

Thanks! We are flying to and from different airports, the price is very similar.

Do you think that's better then doing Seattle down?

"Do you think that's better then doing Seattle down?"

Do you mean starting from SF? If not, what do you mean by "that"?