Salesman, with 30+ years in sales, I can relate to the topic. If you visit my site (www.outsource-sales.net), you'll see that I've been deeply involved in some massive sales initiatives (some have stretched to 18 to 24 months).
When the complexity of the sale impacts the sales cycle, I've found the following formula extremely invaluable:
1. diligently seek out leverage partners *; and,
2. during the early stages, work them fastidiously; and,
3. broaden your base of contacts within the account (remember that "working down" is always better than trying to climb within the account); and,
4. religiously research in order to gain an intimate understanding of ALL the dynamics within the organization (from shareholder motivation to "politics");
If you follow this approach, you'll find yourself becoming the "trusted advisor".
* In the technology business, there is generally an organization adding value to your technology (VARs, OEMs, etc.). In order to optimize your position within the account, you need to uncover who can leverage your offering within this account. Ask yourself, "Other than you, who can profit from the decision?" Work that into a leveraged position ...
Good luck & Good selling!
Pat