Pretty much agree with leaving Dragonite in A-Tier. His versitality is top-notch and enables him to effectively perform various roles that range from Parashuffler to Revenge-killer, plus Multiscale is a undeniably huge boon for Dragonite that affords him more chances to set-up and adds a more-than-welcome coating of protection that bolsters his defenses. In fact, Dragonite actually fits the description for A-Tier 'Mons:
Reserved for Pokemon who can sweep or wall significant portions of the metagame, but require some support or have some flaws that prevents them from doing this consistently. Supporting Pokemon in this rank may give opponents free turns or cannot create free turns easily themselves, but can still do their job most of the time.
Dragonite can sweep significant portions of the metagame, his movepool alone testifies to that. Dragonite does require support primarily in the form of Rapid Spin / Magic Bounce to keep Stealth Rock from breaking Multiscale (and keeping that hefty 25% damage at bay) and alternate weather inducers to remove Sand / Hail from the field, among other things. Dragonite's flaws are also pretty hindering: x4 weakness to Ice, x2 weakness to the ubiquitous SR, susceptible to faster 'Mons that can revenge-kill with ease, notably Scarf Salamence, Scarf Genesect, etc., falls to Ice Shard (but so does every other Dragon that shares the x4 Ice Weakness), and so on. All these limit Dragonite's opportunities at sweeping and his chances of consistently doing so in battles. However, many of these are readily patched with proper team support and even by the metagame itself (an abundance of Rain and Sun easily overshadows the amount of Sand and Hail one will encounter). Too many foibles for S-Tier, but too many selling-points for B-Tier. It's quintessential (or close enough to quintessential) A-Tier.