Krug NV is a delicious champagne and as Jamie Goode mentions in the link above certainly on the toastier end of the scale. It has also leap-frogged Dom Perignon (current vintage not older ones) in price over recent years - a shame.
Questions to ask: Who the present is for (Dad?)? Would they be averse to aging the champagne in good conditions (cellar) for a number of years? Will they appreciate the gift or would they rather have a magnum of something lesser for the same price (Bolly / Veuve magnums at around £70)?
Krug do age their non vintage on the property for a great deal longer than most champagne houses. For example the standard Moët (£50 for a bottle with Swarovski crystals - lol as mentioned by some chavtastic masochist above) is pushed out of the cellar far too soon at the moment which results in an overly acidic blend (in my opinion). This can generally be solved by cellaring it for a few years. Iffy champagnes such as Lanson Black Label can be sorted out with this method also.
If you're looking up to £100 for a bottle I would certainly look at these two:
Dom Perignon 2000 - Moët's prestige cuvée:
The 2000 Dom Perignon is a gorgeous, seductive wine that floats on the palate with remarkable grace. Toasty aromas meld into freshly cut flowers, apricots and pears, with sweet notes of mint and licorice that linger on the long finish. This perfumed, inviting Dom Perignon is elegance personified, and in this vintage the wine fully merits its lofty reputation. Anticipated maturity: 2009-2019. 94/100 Antonio Galloni.
Gosset 1999 (Producing wine in the champagne region since c16):
Very toasty nose with notes of roasted nuts, kaya (coconut and egg) jam and toffee pie. Given the rich appearance of the nose, the palate is surprisingly elegant with some warm apple flavours coming though plus a nice touch of minerality. Crisp backbone of acid and a long, chalky finish. Drink now to 2019. Tasted February 2009. 92/100 Lisa Perrotti-Brown.
Tasting notes taken from
http://www.erobertparker.com