@Tom105 I provide both instant coffee and ground filter coffee. I wouldn't personally bother with beans and a grinder as I think it is just more mess for the guests or I to clean up after. The guests who use the filter coffee tend to leave behind a bit of a mess even if they try to clean up after themselves. I have an espresso type coffee machine with a milk frother, but this rarely gets used (luckily as it's also a bit of a pain to keep cleaning) as I also have caffetieres, which are much quicker to use/clean.
It's good to have the instant coffee as an option for guests who can't be bothered to make the filter stuff. You can get some pretty good 'barrista' style ones that taste almost like filter. They come in little metal tins with a resealable lid. They are more expensive than the regular filter ones, but here anyway, they seem to often be on half price offer at the supermarkets, so it works out the same.
Re brands of coffee, I don't really have a preference, but usually buy Lavazza for filter. What I've found is, that guests who use a lot of the filter coffee often replace it before they leave, which no one does with the instant coffee, teas or sugar. I guess they feel bad because, even though it's been offered to them, it's expensive. So, I actually haven't had to buy any in a while!