If you have no concerns with the car, then I'm sure it'll be fine.
I've taken my Vibes on long roadtrips without any worries. In less than a year of ownership, the '05 GT has taken us from Texas to Michigan and from Texas to Florida without incident. In just a couple weeks, I'll be taking the GT on a 1200 mile trip from Texas to Virginia, too.
The '06 Base before it took many similar trips. I bought it with 110K miles on the odometer and gave the keys to my dad at ~230K after only owning it for about 4 years (roughly 30,000 miles per year). A couple of those trips were heavy loaded, too, including one where I pulled a lightly loaded Uhaul trailer from Florida to Texas when we moved. Other trips had a cargo box or bikes on the roof.
I've never gotten particularly great mileage with either of my Vibes. With both cars, my daily 50/50 mix is around 24mpg and my typical road trip mileage was 27-28 loaded down. The trip with the Uhaul was abysmal and not worth discussing. The trip with the bikes on the roof was pretty bad, too, so I'm not going to make that mistake again. I did get close to 30 in the Base on one trip to Missouri, when I didn't have the cargo box and I only had enough clothes for my daughter and I for a weekend.
Pics of various road trip configs over the years:
2005 Vibe GT ~ Platinum
2006 Vibe ~ Lava, Base, Auto
2005 Corolla S ~ Silver Streak Mica, Manual (Wife's)
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete fools.