Despite concern over high gas prices, improving economic conditions and a pent up demand for travel are moving Americans to spend nearly $16 billion more on summer travel in 2011 than they did in 2010. This is according to a survey released today by global travel assistance company Mondial Assistance USA and its Access America brand of travel insurance. Nearly one half (45%) of Americans say they’re confident (30% very/15% somewhat) that they’ll take a summer vacation this year, up 5 points from last year, and up 10 points in the last two years. In all, Americans plan to spend $86.4 billion on summer vacations in 2011.

Not only are more Americans intending to travel on vacation this summer, but those that are anticipate spending more this year. The average family intends to spend $1,704 this year; up from the $1,567 those who were confident they’d travel last year anticipated spending. This represents an increase of 9% over last year.

With more Americans confident they’ll travel this summer, and with those who intend to travel expecting to spend more than last year, the overall projected spend on vacations this summer is up 22% this year over last year, rising to $86.4 billion.

Men (51%) are significantly more confident than women (40%) to say they’ll get away, as are those in the Northeast (53%) compared to Americans living in the South (47%), West (46%) or Midwest (36%). Perhaps not surprisingly, those whose family earns in excess of $75,000 per year are most likely (62%) to be confident they’ll take a vacation, followed by those who earn between $25K and $75K (44%) or less than $25K per year (28%).

But it’s not all roses. Among those who are confident they’ll take a vacation, a majority (54%) say that high gas prices concern them (including 62% of those with children), making gas prices far more concerning on the whole than other things like bad weather (30%), rising travel costs (28%), the economic uncertainty (24%) or terrorism (16%).

Perhaps as a result of all sorts of uncertainties, nearly two in ten (16%) Americans say that events of the past year, including dramatic weather, terrorism, civil unrest, volcano eruptions, and tsunamis, has made them more likely to purchase travel insurance. This proportion rises to 33% among Hispanic Americans.

When getting ready to leave the house to embark on a trip, 12% of Americans say they often have to turn back because they thought that they’ve forgotten something important like turning off the oven, closing the garage, or something about the dog or kids, etc. In fact, 4% of Americans say they have to turn around every time they leave the house for a trip, representing roughly 1 million American adults who confess that they’re perhaps either really forgetful or obsessive compulsive.

But where things really get interesting is in the blame game. Two in ten (21%) women say that it’s their partner that is usually the one that makes them turn back to the house most often, while one in three (32%) men blame it on their partner. That makes men 50% more likely than women to blame their partner for the last-minute turnaround.