Just something to add. Putting your tank spam macro with your dps spam macro is the way to go. I agree what the others have said. Right now I am working on leveling my dk's They are 74 and I have 4 of them with 1 priest. My tank is speced frost and this is the macro I use. The macro is long so I needed to download macaroon. I use macaroon on my other dk's so I have enough space for their cast sequence. I have two tank macros. One macro is for single target and the other is for aoe.

Single Target Macro:

/run SetCVar("Sound_EnableSFX","0")
/use 13
/use 14
/cast Rune Strike
/cast Blood Fury
/run SetCVar("Sound_EnableSFX","1")
/startattack
/follow Focus
/castsequence [target=focustarget] reset=nocombat Plague Strike, Icy Touch, Blood Strike, Blood Strike, Obliterate, Plague Strike, Icy Touch, Obliterate, Obliterate, Frost Strike,

AOE Tank Macro:

/run SetCVar("Sound_EnableSFX","0")
/use 13
/use 14
/cast Rune Strike
/cast Blood Fury
/run SetCVar("Sound_EnableSFX","1")
/follow focus
/startattack
/castsequence [target=focustarget] reset=nocombat Icy Touch, Plague Strike, Pestilence, Howling Blast, Blood Boil, Frost Strike, Icy Touch, Plague Strike, Pestilence, Howling Blast, Blood Boil, Frost Strike

I use focus so it will be diferent than FTL setup. The good thing about macaroon is my dps DK's have their dps macro bound to key 2 and key 3. My tanks Single Target Macro is key 2. My aoe tank macro is key 3. Because I have both key 2 and 3 bound to the One DPS macro it never screws up my sequence if I am shifting from AOE tanking to Single Target Tanking. My advice to you is download macaroon and use it if you need long macros. If you have it great. I chose frost as my tank because my other dk's cover the blood aura and unholy aura. I have all the group buffs each spec dk can offer. The frost tank is very nice right now adding all the special abilities buffs and resist aura to the group. Dk's have many tank options so choose what suits your needs. Goodluck.