I am trying find a decent vacation place to meet up with a friend from
Adelaide, Australia somewhere between there and Washington DC, where I
live. What country (pleasant to travel to/in) would be approximately
midpoint between Washington DC and Adelaide
Australia?

Hello ndm52:

Thank you for the fascinating question!

If you want a place to meet that's geographically midway between
Adelaide and Washington D.C., then that is definitely going to place
you somewhere in the mid-Pacific. Luckily for the two of you, there
are *many* "pleasant" places to visit in that region. :-)

If you want to get as close as possible to an equal distance for both
travelers, I would suggest either

Hawaii, USA

or 

Kiritimati (formally Christmas Island), Republic of Kiribati

While Hawaii will definitely be easier to get to (more flights, likely
cheaper flights), Kiritimati is certainly more "exotic" - as well as
affordable once you're there.

The following are some good links to look into for both destinations.


Hawaii
******

Hawaii - The Island of Aloha
http://www.gohawaii.com/

Hawaii - Explore Paradise
http://www.hawaii.com/

Hawaii State Vacation Planner
http://www.bestplaceshawaii.com/

Alternative Hawaii - The Hawaii Ecotourism Site
http://www.alternative-hawaii.com/

The Hawaiian Historical Society
http://www.hawaiianhistory.org/


Kiritimati
**********

Republic of Kiribati - Travel And Accommodation Guide
http://www.janeresture.com/kirricom/

Kiribati: Air Travel
http://www.collectors.co.nz/kiribati/air.html

Kiribati
http://www.pacificislandtravel.com/kiribati/about_destin/kiritimati.html

Pictures
http://www.erisdesign.com/tahiti/xmas/


If you were both willing to travel a little further, you could also
take in French Polynesia, which includes the islands of Tahiti and
Bora Bora.

http://www.polynesianislands.com/fp/

If you wanted to be unique and travel "the other way" round the globe,
you could meet in Kenya or Tanzania.

Kenya Travel Guide
http://www.bwanazulia.com/links.html

Tanzania Links
http://www.utalii.com/Tanzania_Links/Links.html


I hope that this information helps you in deciding your mutual meeting
place. If you need any clarification of what I've written, please ask
using the Clarification feature - before you rate this answer.

Thanks again.

websearcher-ga


Search Strategy:

hawaii travel
://www.google.com/search?q=hawaii+travel&hl=en&lr=&ie=UTF-8&safe=off&start=20&sa=N

hawaiian history
://www.google.com/search?q=hawaiian+history&hl=en&lr=&ie=ISO-8859-1&safe=off

Kiritimati travel
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&safe=off&q=Kiritimati+travel

Kiritimati 
://www.google.com/search?q=Kiritimati+&hl=en&lr=&ie=ISO-8859-1&safe=off

"french polynesia" links
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&safe=off&q=%22french+polynesia%22+links

Kenya links
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&safe=off&q=kenya+links

Tanzania links
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&safe=off&q=tanzania+links

This was a very quick, thorough and helpful answer to my question.