Vodka

Vodka is an European clear distilled alcoholic drink that has been one of the most popular drinks across the world .

You'll find it to be the most popular spirit in drink making because of it's neutral taste and absence of flavour and colour.

Vodka often replaces Gin in many traditional cocktails

Vodka is known to be good for the heart, and if consumed in moderation, can prove to be good for cardiovascular health

Note that these days there are flavoured Vodka available in the market too, and some cocktails do make use of them.

Baileys

Bailey's Irish Cream is an Irish cream liqueur, a liqueur is an alcoholic drink made of distilled spirits and flavorings such as sugar, fruits, herbs, and spices. They can be rightfully christened as the descendants of herbal medicine. The Bailey's Irish Cream is a sweet, cream and cocoa flavoured thick liqueur with Irish Whiskey being the base alcohol and is one of the most popular liqueurs used in cocktail creation.

Discontinued by Diageo after two years of launch in 2003 due to plummeting sales, it was a low alcohol and long version of Bailey’s Irish Cream. It was available as a test run in Australia and New Zealand and was never rolled out internationally.

Sprinkled Freshly Ground Coffee

Coffee or roasted coffee beans brewed in hot water, is the most popular drink that probably competes only with tea in the non-alocholic beverages category. Coffee being a rich source of caffeine it can help the human body overcome fatigue and improve physical performance and also lower risks of several conditions like Type II Diabetes, Cancer and Alzheimer's and Parkinson's disease.
Coffee liqueur is a popular and brands like Kahlua and Tia Maria are regulars in cocktails, but often brewed non alcoholic coffee is used in cocktails too, hot black coffee with Rum and whipped cream is what makes a Troical Coffee Cocktail for you, and being a caffeine rich liquid, it is a strange combination with alcohol since it tends to interact with the body and do just the opposite of what alcohol does, that it, tries to keep you alert and awake.

Or Cinnamon

Cinnamon is a very popular spice used world over, obtained from the inner bark of the trees of the genus Cinnamomum. Cinnamon is used in a wide variety of cuisines, sweets, breads and tea and is a dominant flavour in Cola too. Cinnamon trees are grown for two years befiore harvesting them by cutitng the stems at ground level, leaving stumps of trunks from where new shoots grow back and the tree growns again. The cut down stems are immediately processed, the outer bark is scraped off and the stem is beaten evenly with a hammer to loosen the inner bark which is then pried off in long rolls, dried and cut into pieces for sale.
Both Cinnamon Sticks and Cinnamon Powder is used in cocktails to add that sweet and woody flavour to the drink. Alternatively if you are not comfortable with the Powder and the recipe doesn't explicitly asks for Cinnamon Powder you can use a drop of Cinnamon Oil instead.
Note: Cinnamon Leaf Oil has a musky and spicy scent, and a light-yellow tinge that distinguishes it from the red-brown color of cinnamon bark oil Cinnamon leaf oil is lighter, cheaper and ideal for regular use. Although cocktail creation is an art and you can experiment with both.