It is about a 10-15 minute taxi ride from the airport, which is very close and perfectly convenient. There isn't really much to do in the Alajuela airport (that I discovered, anyway) but that didn't bother me because I was just held over there and wasn't expecting to be too entertained. Just be aware that not all taxis in the area will know the B&B by name, so you'll want to have the (approximate) address on hand just in case.
I stayed at Vida Tropical 3 separate nights during my stay in Costa Rica - twice with a friend and once with my boyfriend. The B&B fit my needs well as I was not looking for luxury, but a comfortable, safe, affordable place to stay near the airport. I cannot say enough to say how great and helpful Isabel (the owner) was. She had a taxi pick us up from the airport, greeted us warmly each time we arrived, answered all of our questions and helped us in whatever way we needed (food, taxis, suggestions on where to go, when to arrive to the airport, etc.). Her husband owns a restaurant nearby (Jalapenos) that we visited and on my second stay she arranged for us to have carryout delivered by a taxi. The food was so good and it was so convenient (especially getting in after dark after a day of traveling) that I did this my last night there, as well. To be clear, she wasn't pushing her husband's restaurant - she double checked on my third night to make sure I didn't want something different. Isabel's staff took care of things when she wasn't around with no problems.