Need some ideas on which race and skills to spec into that would define this type of gameplay(tanking while having some kind defensive casting abilities). I plan on using mace and shield, everything else you can tinker with.

Imperial lends very well to a typical paladin. Level up One-hand, block, heavy armour, restoration. Can add in armourer and enchanting

I have a nice build for a Pally/Monk

http://skyrimcalculator.com/#12087


he has every thing unarmed Monk fighting skills lol using heavy armor gloves as your wep's the better the armor the more DMG out put
Lots of heals and can sneak and cast spells and no one will know you are there fun yes
as for armor I would use robes cast Alt spells for armor you can enchant your robes for more HP or resist trust me is fun to play

Most races work well for this sort of character.

I'm also planning a heavy armor character as well who'll focus on shields and maces and I'll be going with a Breton for the resistance bonuses. I'm not planning on a Paladin, so I won't be doing much with magic, but Bretons certainly lend themselves well to this. On that note a High Elf will give you a nice boost on the magic side of things which will let you focus more on improving your health and stamina, and their ability to rapidly regenerate magicka further reduces the need to boost your magicka pool or use magicka regeneration items.

The big combat races, Orcs, Nords, and Redguards are also natural fits.

If by "Monk" you referring to the RPG staple that focuses on unarmed combat you should give Khajiit consideration. Since this is no longer a skill that can be pursued this is a less feasible means of defending yourself, but Khajiit start with a nice bonus here. You can get enchantments to boost this down the road.

Wood Elves, Dark Elves, and Argonians, don't have the best racial advantages for this sort of character but they're still quite feasible. The Wood Elf's ability to command animals may be appealing, the Dark Elf's fire resistance is a nice perk, and the Argonian have a health regeneration ability that fits the Paladin archetype nicely.

Purist?

Paladin -> Heavy Armor, One-Handed, Block, Two-Handed, Restoration, Smithing. Swords, shields, maces. No bows, no axes. I'd go about a 1:2:2 ratio on M:H:S.

Monk -> No Armor (Robes), "Brawling", One-Handed, Alchemy, Enchanting, Alteration, Conjuration, Restoration. Maces or staffs only (no Destruction). 2:1:2 ratio.

Just how I'd build.