Yes, acclimatization is strongly recommended in order to avoid altitude sickness as the Marathon route goes at high altitudes from 3440 to 5360 meters. You may purchase one of our treks: 14-day acclimatization or 10-day acclimatization . Otherwise you should have you own acclimatization program, during which you may stay at one of our friends.
The way from Katmandu to Namche will take two hiking days. You may take a morning flight Kathmandu-Lukla from KTM airport (the earlier the better) – two-way ticket will cost around $360. Also you will have to buy TIMS in KTM for $25-40, and a trekking permit on your way from Lukla to Namche for 3000 Rs.
From Lukla you hike north along the river valley to Phakding or better Benkar, or better Monjo or Jorsalle and stop here for overnight. You may stay at one of the guesthouses we listed here or any other. The next day you hike to Namche Bazaar, where you will live while having your acclimatization program.
If you purchase one of our acclimatization treks, you will be leading to Namche by our guide. Otherwise you can buy our Sleep-and-Run package and have some advantages of communicating with the Marathon organizers and other participants and some conveniences also.