What kind of grad program are you starting?
The C-C dictionary licensed for PlecoDict 2.0,《现代汉语规范词典》(Standard Dictionary of Modern Chinese), has entries for 13,000 characters and 68,000 words and is comparable to the Webster's Collegiate or American Heritage Dictionary for English. It's a very good dictionary for native Chinese speakers who need a dictionary for modern Chinese.
《漢語大辭典》you mentioned has 21,000 characters and 360,000 words, and has a lot more entries for classical Chinese. It's like the Oxford English Dictionary, very comprehensive but not very practical for most people.
If you need a classical Chinese dictionary, I would recommend getting a smaller, more practical classical Chinese dictionary such these:
http://movie.joyo.com/detail/product.as ... T_SMO&uid=
古汉语常用字字典 for characters (6400 commonly classical Chinese characters)
http://movie.joyo.com/detail/product.as ... 28-3427437
古代汉语词典(精) for words (10,000 characters; 24000 words, including proper names)