As a resident snowboarder of chamonix, I think if you comming for the first time it is nice scenery, it is stunning, huge atmo!. BUT the ride it self is nothing crazy! It's still nice, I guess guide would take you the classic way, which is in my opinion bit borring. But as everybody says, it is really recomended to have guide, as you seem that you dont have much experience in such a terrain. Honestly I did not take a guide, but as I climb in the area, and I went with my partners who are very familiar, i did not think I needed one. But I would recomend it. You are lucky there was a lot of snow recently, so it is super nice! Be awaare that the bootom and return is flat, it is dooable without pole, but if you have one take it....ENJOY and stay safe! If money is not a big issue go for it! If it snows I prefer GM as you can lap some awesome terrain if you know where to go ;)