I'm gonna bite the bullet and send the younger son (who lives in Boise), his accoustic guitar, which has been left with me for at least 10 years. I've bought a hardshell case to protect it and will overwrap it with well taped cardboard. Having never posted something so large (110cmx 30cmx18cm) and weighing around 8 or 9 kg, any recommendations on which company to send it via?
Try these people to give you a comparison - https://www.parcel2go.com - We use them all the time to send stuff around the world, including the USA and last week to South Africa
Always use Parcel2Go myself; they are cheaper than direct to most couriers including UPS, DPD, ParcelFarce, etc.
I use www.parcelsupermarket.com for large international packages like the Hyper long range fuel tanks.