Today, I'm going to give some plain talk about four companies that I am building my retirement portfolio around. I'm not going to feed you a ton of stats. Those numbers are -- no doubt -- important, but they are also readily available elsewhere.

Instead, I'd like to do something I always appreciate as a reader: take you on a simple walk-through of my reasons for owning these stocks.

Though I can't promise these companies will be winners, you can rest assured that if they aren't, I will be feeling the pain right along with you. And for those who (wisely) want some context, my longtime CAPS profile says that I rank in the top 5% of investors at the Fool; that's got to count for something.

Add these companies to your Watchlist and you'll be able to stay up-to-date on all of their latest news. Read all the way to the end, and I'll give you access to a second opinion: five excellent stocks from one of the Fool's most seasoned investors.

Apple (Nasdaq: AAPL)
If the last 10 years have taught us anything, it's that innovation always wins out. That's a double-edged sword, as competitive advantages are tough to come by, and the mighty can fall quickly from their perch on top of the mountain.

But the fact of the matter is, Apple is a company that has innovation in its DNA.

No, Steve Jobs is no longer with us; his greatness, however, is -- in the form of iPhones, iPads, and, most important, in the form of those products he helped design which the public does not yet know about (e.g., the recent rumors of a revamped Apple TV). Apple is poised for so many possible futures one could arguably assert that they will one day unseat the likes of Netflix in streaming movies or Sirius (Nasdaq: SIRI) in offering news, music, and sports over the airwaves.

In the interest of full disclosure, Apple now sits at 8.1% of my portfolio.

Google (Nasdaq: GOOG)
To be honest, I think it would be difficult to argue that Google shouldn't be a part of an investor's watchlist, if not their portfolio. If Apple is a good example of a company with multiple futures, then I think Google is an even better example.

At its core, Google is a search and advertising business -- and the company has been wise to keep its focus on this throughout the years. But it has its iron in several different fires as well. Chrome, YouTube, and Android are all wildly popular and growing by the day. Google+ is trying to take social traffic from Facebook. And there's even a Google Offers program that could one day rival Groupon, Living Social, and Travelzoo (Nasdaq: TZOO).

Right now, Google accounts for 7.2% of my portfolio, and I'll be looking to add more soon.

Coke (NYSE: KO)
Coke really couldn't be more different from Google or Apple. But that's the kind of diversification that any portfolio needs to perform during the ups and downs of the market.

The bottom line with Coke is this: The brand is just about the most ubiquitous in the world. I've traveled to Asia, Europe, and South America, and in every instance, Coke was everywhere.

There'll always be competition -- sometimes from the usual suspects like PepsiCo, and other times from more interesting start-ups, like do-it-yourself soda maker SodaStream (Nasdaq: SODA). But if the past is any indication of the future -- and sometimes, I believe it is -- then one thing is for sure: Coke will still be a leading brand 20 years from now.

Coke currently makes up 5.4% of my portfolio.

Zipcar (NYSE: ZIP)
It stands to reason that my portfolio has some room for a spunky upstart. That position goes to car-sharing specialist Zipcar.

Zipcar is capitalizing on a shift that I think is already under way in many urban areas: a second-guessing about the necessity of car ownership. In much the same way the recent financial mess has made us rethink the American imperative of home ownership, many Zipsters (as they're called) have decided that the benefits of car ownership no longer outweigh the costs.

The company recently entered into an agreement with Ford (NYSE: F), whereby the carmaker will be providing the vehicles for Zipcar's college campus locations. Ford believes this will engender brand loyalty when the students graduate into the real world. It will be interesting to see if they will be, instead, just further reinforcing the idea that car ownership is only for the super-wealthy.

Currently, as it's still in its early stages, Zipcar makes up only 0.5% of my portfolio, but I will likely be adding more shares in the future as the company's market opportunity becomes clearer.

A second opinion for a master investor
It just so happens that all four of these stocks are also current selections of The Motley Fool's Million Dollar Portfolio (MDP) service. That service will be opening to new members next week -- the only time it will be doing so this year.

The service is run by Ron Gross, who successfully ran his own hedge fund for nine years before starting up MDP. He has put together a special free report, "5 Stocks for the Next Bull Market," to give you a taste of what the MDP experience is all about. This report will only be available for a short time, so I encourage you to get your free copy today, before time runs out.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.