I’ve been intermittently working on a round-the-world flight in the TBM 930 with a friend; it covers a lot of territory with a cruise around 330 KTAS, can go over a lot of weather at up to FL310, but still “feels” like a small plane. We’ve handled ocean crossings including going from Indonesia to northern Australia, and eastern Australia to southern New Zealand, with the longest legs being about 4 hours.
IRL you might not want to do those ocean crossings in a single-engine, of course, because you’d have to ditch in the ocean in case of mid-flight engine failure.
On PC I’d recommend the Working Title G3000 mod which improves the avionics, but you can’t currently use that on Xbox – however the performance of the plane itself remains fine in stock, and doesn’t prevent me from recommending it.
For slower/lower trips in a piston, the Cirrus SR-22 as mentioned has good speed (up to 180 KTAS at cruise), and having G1000 avionics you can use the G1000 NXi add-on from the Marketplace (beware it’s an early access beta, but it’s a big improvement over the current stock G1000 and is improving fast).
I also am fond of the Diamond DA62 which can reach similar speeds and is a twin-engine, but there are some performance problems with the stock version, and the performance mod for it is not available on Xbox so your mileage may vary.
(I do most of my trips in shorter chunks, as 1-2 hour VFR journeys around the US west coast, and am partial to the Flight Design CTSL. This is not fast, and has no autopilot, but it represents the kind of plane I would be likely to have access to if I ever get my butt in gear and go for a sport pilot’s license!)